WEBVTT 00:00:00.000 --> 00:00:01.720 Okay, so I want you to imagine you're standing 00:00:01.720 --> 00:00:04.059 on a street corner. Let's say, I don't know, 00:00:04.120 --> 00:00:07.440 Fifth Avenue and 34th Street in Manhattan. Or 00:00:07.440 --> 00:00:09.460 maybe you're deep in the financial district in 00:00:09.460 --> 00:00:11.740 Hong Kong with that, you know, that dense human 00:00:11.740 --> 00:00:13.820 energy all around you. You just stop walking 00:00:13.820 --> 00:00:16.579 for a second. And you tilt your head back to 00:00:16.579 --> 00:00:18.660 look at the building right in front of you. And 00:00:18.660 --> 00:00:20.440 you keep tilting. You keep tilting. You tilt 00:00:20.440 --> 00:00:22.899 your head back until... your neck actually starts 00:00:22.899 --> 00:00:24.800 to hurt until you can feel the vertebrae kind 00:00:24.800 --> 00:00:26.940 of crunching a little bit. And you're looking 00:00:26.940 --> 00:00:30.940 up at this just sheer cliff face of glass and 00:00:30.940 --> 00:00:34.399 steel that seems to just disappear somewhere 00:00:34.399 --> 00:00:37.299 into the clouds. It's really the defining image 00:00:37.299 --> 00:00:40.049 of the modern city, isn't it? But if you stand 00:00:40.049 --> 00:00:42.369 there long enough looking up at that angle you 00:00:42.369 --> 00:00:44.789 start to realize something a little unsettling. 00:00:44.869 --> 00:00:47.369 You realize that you're a biological organism. 00:00:47.570 --> 00:00:50.750 You know a soft relatively fragile hairless ape 00:00:50.750 --> 00:00:53.130 standing the base of a million ton needle that 00:00:53.130 --> 00:00:55.270 is for all intents and purposes balancing on 00:00:55.270 --> 00:00:57.570 a pinhead. A needle that's actively fighting 00:00:57.570 --> 00:00:59.890 gravity fighting the wind every second of the 00:00:59.890 --> 00:01:03.950 day and it's housing thousands of other hairless 00:01:03.950 --> 00:01:06.430 apes. And yet, what do we do? We walk inside, 00:01:06.670 --> 00:01:09.230 we press a button, we shoot up 100 floors to 00:01:09.230 --> 00:01:11.930 go grab a latte, and we don't even blink. We've 00:01:11.930 --> 00:01:14.750 completely normalized what is objectively an 00:01:14.750 --> 00:01:17.189 impossible feat of engineering. That is exactly 00:01:17.189 --> 00:01:19.209 what we're doing today. We are stripping back 00:01:19.209 --> 00:01:21.810 the skin of the city to do a deep dive into the 00:01:21.810 --> 00:01:24.689 skyscraper. And I want to be really clear about 00:01:24.689 --> 00:01:28.319 our mission here. This isn't just going to be 00:01:28.319 --> 00:01:30.659 a list of the top 10 tallest buildings. We're 00:01:30.659 --> 00:01:32.659 not doing the tourist tour. No, absolutely not. 00:01:32.700 --> 00:01:34.379 We're looking for the engineering breakthroughs. 00:01:34.379 --> 00:01:36.579 We really want to dig in and identify the specific 00:01:36.579 --> 00:01:40.500 mechanical and physical problems that had to 00:01:40.500 --> 00:01:42.700 be solved. The bottlenecks that basically stopped 00:01:42.700 --> 00:01:45.519 us for. Thousands of years. And the aha moments. 00:01:45.640 --> 00:01:47.959 And the aha moments, exactly. The flashes of 00:01:47.959 --> 00:01:50.620 genius that finally allowed us to, you know, 00:01:50.620 --> 00:01:53.180 live and work in the clouds. We're going to talk 00:01:53.180 --> 00:01:56.140 about the transition from, say, mud brick towers 00:01:56.140 --> 00:01:58.799 in the middle of the desert to these modern tube 00:01:58.799 --> 00:02:04.000 structures. these crazy aerodynamic damping systems 00:02:04.000 --> 00:02:06.620 that are letting us break the kilometer mark. 00:02:06.900 --> 00:02:09.180 We've got a whole stack of source material here, 00:02:09.240 --> 00:02:11.500 architectural histories, engineering journals, 00:02:11.759 --> 00:02:14.080 even some physics breakdowns of wind vortices. 00:02:14.379 --> 00:02:15.979 And what's so fascinating when you look at it 00:02:15.979 --> 00:02:18.259 all together is that the history of the skyscraper 00:02:18.259 --> 00:02:21.580 isn't this clean, straight line of progress. 00:02:21.800 --> 00:02:24.000 It wasn't just, oh, we got better at building. 00:02:24.199 --> 00:02:27.000 It was a series of hard stops. Physics would 00:02:27.000 --> 00:02:29.120 throw a problem at us, we'd get stuck for a few 00:02:29.120 --> 00:02:32.090 centuries, and then someone... somewhere would 00:02:32.090 --> 00:02:34.729 have a truly genius idea. So let's start at the 00:02:34.729 --> 00:02:36.569 very beginning, or I guess let's start with the 00:02:36.569 --> 00:02:38.250 ground rules for what we're even talking about. 00:02:38.389 --> 00:02:40.169 Because when I first started reading through 00:02:40.169 --> 00:02:41.729 this, the first thing I thought was, okay, the 00:02:41.729 --> 00:02:44.490 Great Pyramid of Giza, that was the tallest man 00:02:44.490 --> 00:02:47.009 -made thing on Earth for, what, almost 4 ,000 00:02:47.009 --> 00:02:50.389 years? It was, yeah. It stands at 146 meters, 00:02:50.469 --> 00:02:53.310 which is nearly 500 feet. That is a massive, 00:02:53.349 --> 00:02:56.569 massive structure by any measure. But according 00:02:56.569 --> 00:02:59.409 to all the experts, it doesn't count as a skyscraper. 00:02:59.680 --> 00:03:01.699 It does not. Why not? I mean, it's tall, it's 00:03:01.699 --> 00:03:04.300 manmade, it's iconic. What's the missing ingredient? 00:03:04.759 --> 00:03:06.879 It's a tomb. I mean, the technical definition 00:03:06.879 --> 00:03:09.680 of a skyscraper, if we look at the standards 00:03:09.680 --> 00:03:12.740 set by the Council on Tall Buildings and Urban 00:03:12.740 --> 00:03:14.840 Habitat, which is kind of the official governing 00:03:14.840 --> 00:03:18.199 body for these things, it all hinges on one critical 00:03:18.199 --> 00:03:21.300 word, habitability. So you have to be able to 00:03:21.300 --> 00:03:24.139 actually live inside it or work inside it. You 00:03:24.139 --> 00:03:26.419 have to be able to occupy it, yeah. A skyscraper 00:03:26.419 --> 00:03:28.719 is fundamentally a machine for human occupation. 00:03:29.710 --> 00:03:32.810 The Great Pyramid, on the other hand, is a solid 00:03:32.810 --> 00:03:36.669 pile of limestone blocks with just a few very, 00:03:36.750 --> 00:03:39.449 very narrow, very claustrophobic tunnels leading 00:03:39.449 --> 00:03:42.469 to a burial chamber. The structural logic is 00:03:42.469 --> 00:03:44.810 simple. You just pile rocks until you reach a 00:03:44.810 --> 00:03:46.969 point. Okay, that makes sense. The Eiffel Tower 00:03:46.969 --> 00:03:49.090 is another great example of this. When it was 00:03:49.090 --> 00:03:51.409 built in 1889, it just blew everyone's mind. 00:03:51.490 --> 00:03:53.229 It was the first structure to cross that 300 00:03:53.229 --> 00:03:55.810 -meter mark, which was a huge psychological barrier. 00:03:56.069 --> 00:03:57.610 But you can't live in it. It's the lightest tower. 00:03:57.900 --> 00:04:00.819 Exactly. It's an open framework of iron. You 00:04:00.819 --> 00:04:03.139 can't rent an apartment in one of the girders. 00:04:03.259 --> 00:04:05.719 You can't have an office on the 50th floor because 00:04:05.719 --> 00:04:08.199 there is no 50th floor. There's just air and 00:04:08.199 --> 00:04:10.099 iron beams. So the real engineering challenge 00:04:10.099 --> 00:04:13.240 isn't just make something tall. It's make it 00:04:13.240 --> 00:04:15.439 tall, make it hollow, and then fill that hollow 00:04:15.439 --> 00:04:18.360 space with heavy people, furniture, plumbing, 00:04:18.680 --> 00:04:21.620 partition walls, everything. Precisely. You're 00:04:21.620 --> 00:04:26.079 stacking usable, rentable volume. not just stacking 00:04:26.079 --> 00:04:29.300 mass. And that distinction is what makes the 00:04:29.300 --> 00:04:32.060 history so interesting, because the desire to 00:04:32.060 --> 00:04:34.720 do this, to stack families on top of each other, 00:04:34.779 --> 00:04:37.519 is actually ancient. Right. This is the common 00:04:37.519 --> 00:04:39.360 misconception. I always assumed it was a purely 00:04:39.360 --> 00:04:42.959 modern American invention from, you know, the 00:04:42.959 --> 00:04:45.139 late 19th century Chicago. That's what most people 00:04:45.139 --> 00:04:47.410 think. But the source material points us way, 00:04:47.470 --> 00:04:50.930 way back to imperial Rome. Rome. They have villas 00:04:50.930 --> 00:04:53.149 and forums, not high rises. Well, Rome had a 00:04:53.149 --> 00:04:55.329 serious population crisis. They were constrained 00:04:55.329 --> 00:04:57.490 by the city walls. Land was incredibly expensive 00:04:57.490 --> 00:04:59.529 and they couldn't just sprawl outward. So what 00:04:59.529 --> 00:05:01.230 was the logical solution? They went up. They 00:05:01.230 --> 00:05:03.209 developed these apartment blocks called insulae. 00:05:03.310 --> 00:05:05.629 And these weren't just like two story townhouses. 00:05:05.850 --> 00:05:08.089 Oh, no. These were high rises. We have written 00:05:08.089 --> 00:05:10.769 records from people like the poet Marshall and 00:05:10.769 --> 00:05:12.910 the satirist Juvenal describing them reaching 00:05:12.910 --> 00:05:16.649 10 stories or even more. stories in ancient Rome. 00:05:17.050 --> 00:05:20.129 How do you even build a 10 -story building without 00:05:20.129 --> 00:05:24.250 steel beams or reinforced concrete? Poorly, to 00:05:24.250 --> 00:05:27.329 be honest, very, very poorly. They used a combination 00:05:27.329 --> 00:05:30.490 of timber frames, sun -dried mud bricks, and 00:05:30.490 --> 00:05:33.470 a kind of primitive rubble concrete. The engineering 00:05:33.470 --> 00:05:36.290 was, frankly, terrifying. I'm picturing something 00:05:36.290 --> 00:05:38.509 pretty unstable. You're right, too. They were 00:05:38.509 --> 00:05:40.810 basically stacking heavy, brittle materials on 00:05:40.810 --> 00:05:42.870 top of each other without a proper rigid frame 00:05:42.870 --> 00:05:45.569 to hold it all together. The structural integrity 00:05:45.569 --> 00:05:49.629 was, let's say, suspect. Suspect is a gentle 00:05:49.629 --> 00:05:51.810 word for it, I imagine. It's putting it mildly. 00:05:51.870 --> 00:05:54.230 The poet Juvenal actually wrote about what it 00:05:54.230 --> 00:05:55.810 was like to walk through the streets of Rome 00:05:55.810 --> 00:05:58.569 in constant fear. And he wasn't afraid of muggers. 00:05:58.589 --> 00:06:00.649 He was afraid that a pot would fall off a high 00:06:00.649 --> 00:06:03.300 ledge and crack his skull. Or worse, that an 00:06:03.300 --> 00:06:05.180 entire building would just collapse into the 00:06:05.180 --> 00:06:07.459 street. And that actually happened. It happened 00:06:07.459 --> 00:06:09.399 all the time. There were notorious fire traps, 00:06:09.519 --> 00:06:11.360 too, because they were packed with timber. A 00:06:11.360 --> 00:06:13.939 fire could take out an entire block. It got so 00:06:13.939 --> 00:06:15.740 bad that the emperors had to step in, right? 00:06:15.800 --> 00:06:17.399 The government had to regulate this. They did. 00:06:17.540 --> 00:06:19.839 Emperor Augustus set a height limit of about 00:06:19.839 --> 00:06:23.540 20 to 25 meters. That's roughly 80 feet, maybe 00:06:23.540 --> 00:06:26.779 seven stories. And it wasn't an aesthetic choice 00:06:26.779 --> 00:06:29.680 to protect the view of the Forum. It was a public 00:06:29.680 --> 00:06:33.060 safety measure to stop the death toll. It's probably 00:06:33.060 --> 00:06:36.220 the first example in history of zoning laws being 00:06:36.220 --> 00:06:39.800 driven by repeated catastrophic structural failure. 00:06:39.839 --> 00:06:42.439 So the ambition, the economic driver to build 00:06:42.439 --> 00:06:45.540 high was there, but the material science just 00:06:45.540 --> 00:06:47.689 completely failed them. It couldn't keep up. 00:06:47.730 --> 00:06:49.649 Now, if we jump forward a thousand years or so 00:06:49.649 --> 00:06:51.730 to the Middle Ages, we see another fascinating 00:06:51.730 --> 00:06:54.509 attempt in Bologna, Italy. I've seen the old 00:06:54.509 --> 00:06:56.910 drawings of this. It looks like something straight 00:06:56.910 --> 00:06:58.949 out of a fantasy novel. Yeah, the whole city 00:06:58.949 --> 00:07:02.519 skyline is just towers. It really does. In the 00:07:02.519 --> 00:07:04.759 12th century, Bologna's skyline looked like a 00:07:04.759 --> 00:07:07.860 pincushion. It was absolutely bristling with 00:07:07.860 --> 00:07:10.860 these tall, slender towers. The wealthy families 00:07:10.860 --> 00:07:12.779 built them as status symbols and for defense. 00:07:13.180 --> 00:07:15.379 At its peak, there were somewhere between 80 00:07:15.379 --> 00:07:17.279 and 100 of them. And some of them were seriously 00:07:17.279 --> 00:07:20.040 tall, right? Like modern building tall? Oh, yeah. 00:07:20.220 --> 00:07:22.639 The Asinelli Tower, which is still standing today, 00:07:22.800 --> 00:07:26.560 is 97 .2 meters tall. That is nearly a modern 00:07:26.560 --> 00:07:29.519 30 -story building. Wow. But again, these weren't 00:07:29.519 --> 00:07:32.139 really efficient skyscrapers in the modern sense. 00:07:32.360 --> 00:07:34.279 No, not at all. Because they were built with 00:07:34.279 --> 00:07:36.680 masonry, the walls had to be incredibly thick 00:07:36.680 --> 00:07:38.879 at the base to support that height. So the rooms 00:07:38.879 --> 00:07:41.680 inside were tiny, dark, and cramped. They were 00:07:41.680 --> 00:07:44.180 built primarily for defense and status. Basically, 00:07:44.319 --> 00:07:46.620 my family is more powerful than yours because 00:07:46.620 --> 00:07:49.680 my tower is taller, not for maximizing rentable 00:07:49.680 --> 00:07:51.819 square footage. It was a medieval measuring contest, 00:07:52.040 --> 00:07:54.160 basically. Very much so. But if you want to find 00:07:54.160 --> 00:07:57.000 the true ancestral home of the modern skyscraper 00:07:57.000 --> 00:07:59.519 city, place that actually functioned like a vertical, 00:07:59.680 --> 00:08:01.980 high -density neighborhood, you have to look 00:08:01.980 --> 00:08:04.980 at a really unexpected place. Yemen. Shabam. 00:08:05.420 --> 00:08:07.360 I've read about this. They call it the Manhattan 00:08:07.360 --> 00:08:09.980 of the desert. This place is absolutely incredible. 00:08:10.180 --> 00:08:12.339 It dates all the way back to the 16th century. 00:08:12.579 --> 00:08:15.620 It's a walled city built in the middle of a desert 00:08:15.620 --> 00:08:18.800 wadi, a river valley. To protect themselves from 00:08:18.800 --> 00:08:20.800 Bedouin raids, they couldn't spread out. So again, 00:08:20.939 --> 00:08:22.759 they went up. And they built these tower houses 00:08:22.759 --> 00:08:25.639 out of what? Mud? Sun -dried mud bricks. They 00:08:25.639 --> 00:08:28.720 rise 5 to 11 stories high. 11 stories made of 00:08:28.720 --> 00:08:30.819 mud bricks. That seems impossible. And they're 00:08:30.819 --> 00:08:32.580 still standing today, hundreds of years later. 00:08:32.720 --> 00:08:34.820 Now they require constant maintenance. You have 00:08:34.820 --> 00:08:37.200 to reapply layers of mud plaster because of rain 00:08:37.200 --> 00:08:39.379 erosion, but they function as high density vertical 00:08:39.379 --> 00:08:42.200 housing. Each floor of a tower house serves a 00:08:42.200 --> 00:08:43.840 different function for the family that lives 00:08:43.840 --> 00:08:46.379 there. It's definitive proof that the skyscraper 00:08:46.379 --> 00:08:48.899 isn't a technology. It's an economic solution 00:08:48.899 --> 00:08:51.960 to a scarcity of land. OK, so we've established 00:08:51.960 --> 00:08:53.440 the motivation has been there for centuries. 00:08:53.740 --> 00:08:57.899 Rome, Bologna, 16th century Yemen. So why did 00:08:57.899 --> 00:09:00.429 it take until the late 1800s for... us to really 00:09:00.429 --> 00:09:03.169 break through and build the cities we see today. 00:09:03.389 --> 00:09:06.210 What were the hard physical limits? There were 00:09:06.210 --> 00:09:09.210 two absolute bottlenecks. One was structural 00:09:09.210 --> 00:09:12.610 and the other was, for lack of a better word, 00:09:12.710 --> 00:09:15.169 physiological. Let's tackle the structural one 00:09:15.169 --> 00:09:18.049 first. The source material calls this the masonry 00:09:18.049 --> 00:09:20.929 problem. Right. In all traditional construction, 00:09:21.169 --> 00:09:23.529 from the pyramids to those towers in Bologna, 00:09:23.649 --> 00:09:27.019 the walls are load -bearing. That means the wall 00:09:27.019 --> 00:09:28.700 itself supports the weight of the floor above 00:09:28.700 --> 00:09:30.759 it, which supports the wall above that, and so 00:09:30.759 --> 00:09:33.879 on all the way up. The entire weight of the building 00:09:33.879 --> 00:09:36.639 is channeled down through the walls. So the higher 00:09:36.639 --> 00:09:39.600 you go... the heavier the building gets. Exponentially 00:09:39.600 --> 00:09:42.159 heavier. And as it gets heavier, the walls at 00:09:42.159 --> 00:09:44.360 the bottom have to get thicker and thicker to 00:09:44.360 --> 00:09:46.919 avoid being literally crutched under the compressive 00:09:46.919 --> 00:09:49.320 load. It's that pyramid principle again. And 00:09:49.320 --> 00:09:51.100 eventually you just hit a point of diminishing 00:09:51.100 --> 00:09:52.679 returns where it doesn't make sense anymore. 00:09:52.840 --> 00:09:54.980 You do. And that practical limit was reached 00:09:54.980 --> 00:09:57.220 in Chicago with the Monadnock building, which 00:09:57.220 --> 00:10:00.820 was completed in 1891. It's 16 stories tall, 00:10:00.980 --> 00:10:04.059 which was absolutely massive for its time. But 00:10:04.059 --> 00:10:07.009 to support those 16 stories of brick? The load 00:10:07.009 --> 00:10:09.009 -bearing walls at the ground floor are six feet 00:10:09.009 --> 00:10:11.190 thick. Six feet. That's wider than I am tall. 00:10:11.350 --> 00:10:14.769 Six feet of solid masonry. Now imagine you're 00:10:14.769 --> 00:10:17.330 a shop owner on the ground floor. You want big, 00:10:17.350 --> 00:10:19.870 beautiful display windows to show off your goods. 00:10:20.009 --> 00:10:22.669 You want wide open floor space for your customers. 00:10:22.870 --> 00:10:25.529 But instead, you have these tiny tunnel -like 00:10:25.529 --> 00:10:28.210 entrances and walls that are eating up half of 00:10:28.210 --> 00:10:30.549 your rentable area. You literally couldn't go 00:10:30.549 --> 00:10:32.549 any higher because the building would eventually 00:10:32.549 --> 00:10:35.409 just become a solid brick pyramid at the bottom. 00:10:35.850 --> 00:10:37.789 That's the hard structural ceiling. What was 00:10:37.789 --> 00:10:40.049 the physiological problem? Stairs. It's that 00:10:40.049 --> 00:10:43.389 simple. It's that simple. Before the mid -19th 00:10:43.389 --> 00:10:46.350 century, verticality was a punishment. If you 00:10:46.350 --> 00:10:48.370 lived on the seventh floor of a tenement building 00:10:48.370 --> 00:10:51.509 in, say, 17th century Edinburgh, which also had 00:10:51.509 --> 00:10:54.330 high -rises out of necessity, you were almost 00:10:54.330 --> 00:10:56.470 certainly destitute. You had to haul your water, 00:10:56.570 --> 00:10:59.289 your coal, your groceries, up seven flights of 00:10:59.289 --> 00:11:01.809 stairs every single day. So the penthouse wasn't 00:11:01.809 --> 00:11:05.100 a luxury item. Far from it. The rich lived on 00:11:05.100 --> 00:11:07.100 the first or second floor. The piano nobile, 00:11:07.240 --> 00:11:09.960 the noble floor. The poor lived in the garrets 00:11:09.960 --> 00:11:11.980 and attics at the very top because it was cheap, 00:11:12.100 --> 00:11:13.759 it was hot in the summer, cold in the winter, 00:11:13.860 --> 00:11:16.679 and absolutely exhausting to get to. So to get 00:11:16.679 --> 00:11:19.059 to the modern skyscraper, we needed to solve 00:11:19.059 --> 00:11:21.779 the wall problem and the stair problem. And this 00:11:21.779 --> 00:11:23.960 brings us to what the outline calls the technological 00:11:23.960 --> 00:11:27.379 trinity. These three key inventions that all 00:11:27.379 --> 00:11:30.720 converged between roughly 1850 and 1890 to make 00:11:30.720 --> 00:11:33.179 the modern skyline possible. The safety elevator, 00:11:33.600 --> 00:11:37.860 the steel frame, and the curtain wall, the holy 00:11:37.860 --> 00:11:40.440 trinity of vertical construction. Let's start 00:11:40.440 --> 00:11:42.759 with the elevator. We always credit Elisha Otis, 00:11:42.840 --> 00:11:45.720 but hoists and lifts existed before him, didn't 00:11:45.720 --> 00:11:48.200 they? Oh, sure. Steam -powered hoists were used 00:11:48.200 --> 00:11:50.700 for moving cargo in factories and warehouses, 00:11:50.840 --> 00:11:53.080 but they were absolute death traps. They were 00:11:53.080 --> 00:11:56.159 lifted by a single hemp rope. If that rope snapped 00:11:56.159 --> 00:11:58.879 and hemp ropes frayed and snapped all the time, 00:11:58.940 --> 00:12:01.450 the... platform just plummeted and whatever was 00:12:01.450 --> 00:12:03.129 on it was destroyed. You would never put a human 00:12:03.129 --> 00:12:05.129 being on one of those. So what was Otis's great 00:12:05.129 --> 00:12:07.450 innovation? Elisha Otis didn't invent the elevator. 00:12:07.649 --> 00:12:10.230 He invented the brakes, the failsafe. This is 00:12:10.230 --> 00:12:12.029 the famous Crystal Palace demonstration, right? 00:12:12.629 --> 00:12:15.370 1853 at the Exhibition of the Industry of All 00:12:15.370 --> 00:12:18.700 Nations in New York. It's pure showmanship. He 00:12:18.700 --> 00:12:21.059 gets on this hoisting platform, has it raised 00:12:21.059 --> 00:12:23.840 high above the crowd. Then he dramatically orders 00:12:23.840 --> 00:12:26.440 his assistant to cut the single supporting rope 00:12:26.440 --> 00:12:28.379 with an axe. The crowd must have freaked out. 00:12:28.480 --> 00:12:31.220 They gasped. They thought they were about to 00:12:31.220 --> 00:12:34.179 witness a man plummet to his death. But the rope 00:12:34.179 --> 00:12:36.740 is cut and the platform drops just a few inches 00:12:36.740 --> 00:12:40.059 and then stops dead with a loud clang. He tips 00:12:40.059 --> 00:12:43.779 his hat and says, all safe, gentlemen. All save... 00:12:43.779 --> 00:12:46.320 How did it work? It seems like magic. It was 00:12:46.320 --> 00:12:49.519 a brilliantly simple mechanical solution. He 00:12:49.519 --> 00:12:52.220 used a large leaf spring mechanism at the top 00:12:52.220 --> 00:12:54.419 of the elevator car. While there was tension 00:12:54.419 --> 00:12:57.059 on the rope as it was pulling the car up, that 00:12:57.059 --> 00:12:59.139 tension held the spring in a compressed state. 00:12:59.399 --> 00:13:01.500 But the moment the rope was cut, the tension 00:13:01.500 --> 00:13:04.009 vanished. The spring was released and it snapped 00:13:04.009 --> 00:13:06.549 outward. And it grabbed onto something. It engaged 00:13:06.549 --> 00:13:09.269 these heavy -duty ratchets like big metal teeth 00:13:09.269 --> 00:13:11.529 that physically clawed into the guide rails on 00:13:11.529 --> 00:13:13.909 either side of the elevator shaft. The system 00:13:13.909 --> 00:13:16.710 works because the main rope fails. It's a true 00:13:16.710 --> 00:13:20.269 fail -safe. And that one demonstration completely 00:13:20.269 --> 00:13:23.529 changed real estate economics forever. Overnight. 00:13:23.870 --> 00:13:26.289 The upper floors went from being the least desirable 00:13:26.289 --> 00:13:29.009 to the most desirable. You got better light. 00:13:29.149 --> 00:13:31.210 You got cleaner air away from the horse manure 00:13:31.210 --> 00:13:33.190 and noise of the street. You got the incredible 00:13:33.190 --> 00:13:37.389 views. The entire concept of the penthouse was 00:13:37.389 --> 00:13:41.070 born the moment Elisha Otis cut that rope. OK, 00:13:41.169 --> 00:13:43.350 so now we can get people up there safely. Problem 00:13:43.350 --> 00:13:46.070 one is solved, but we still have the six foot 00:13:46.070 --> 00:13:48.389 thick walls. We need to get rid of the masonry 00:13:48.389 --> 00:13:50.429 problem. And this is where the Industrial Revolution 00:13:50.429 --> 00:13:53.740 provides the other key ingredient, steel. We 00:13:53.740 --> 00:13:56.500 move from building with stone, which is fantastic 00:13:56.500 --> 00:13:59.100 in compression, but terrible in tension. It cracks 00:13:59.100 --> 00:14:01.440 if you pull it. To steel, which can handle both 00:14:01.440 --> 00:14:04.360 forces beautifully. Exactly. But the real architectural 00:14:04.360 --> 00:14:06.559 breakthrough wasn't just the material. It was 00:14:06.559 --> 00:14:08.960 shifting the entire load path of the building. 00:14:09.360 --> 00:14:12.679 In 1885, an architect in Chicago named William 00:14:12.679 --> 00:14:14.919 LeBaron Jenny was designing the home insurance 00:14:14.919 --> 00:14:18.610 building. And he had a radical realization. Instead 00:14:18.610 --> 00:14:21.230 of stacking heavy bricks, why not build a rigid 00:14:21.230 --> 00:14:24.850 cage first? A skeleton. A skeleton. A three -dimensional 00:14:24.850 --> 00:14:28.190 grid of iron and later steel columns and horizontal 00:14:28.190 --> 00:14:32.350 beams, all bolted or riveted together. This cage, 00:14:32.529 --> 00:14:35.490 this internal skeleton, carries the entire weight 00:14:35.490 --> 00:14:38.230 of the building. The walls suddenly stopped doing 00:14:38.230 --> 00:14:40.149 the heavy lifting. They stopped doing any lifting 00:14:40.149 --> 00:14:42.509 at all. Which leads directly to the third innovation, 00:14:42.870 --> 00:14:46.110 the curtain wall. I love this term because it 00:14:46.110 --> 00:14:48.990 sounds so delicate and decorative, but it really 00:14:48.990 --> 00:14:51.620 represents this massive. engineering shift. It 00:14:51.620 --> 00:14:53.940 is absolutely radical because the steel frame 00:14:53.940 --> 00:14:56.539 is holding the building up. The outer walls are 00:14:56.539 --> 00:14:58.960 just hanging off the frame like, well, like curtains. 00:14:59.120 --> 00:15:01.600 Their only job is to keep the weather out and 00:15:01.600 --> 00:15:03.740 the people in. So you can make them out of anything. 00:15:03.960 --> 00:15:05.519 Anything lightweight. You could make them out 00:15:05.519 --> 00:15:08.240 of thin panels of stone, terracotta, aluminum. 00:15:08.480 --> 00:15:10.720 And this is the crucial part for the 20th century 00:15:10.720 --> 00:15:12.899 glass. This is why that building in Liverpool 00:15:12.899 --> 00:15:16.440 Oriole Chambers built way back in 1864 is so 00:15:16.440 --> 00:15:18.500 important, even though people at the time apparently 00:15:18.500 --> 00:15:22.379 hated it. Oh, they despised it. One critic called 00:15:22.379 --> 00:15:25.100 it a large agglomeration of protruding plate 00:15:25.100 --> 00:15:29.139 glass bubbles. It was hideous to the Victorian 00:15:29.139 --> 00:15:32.940 eye, which was used to solid heavy masonry. But 00:15:32.940 --> 00:15:35.799 Peter Ellis, the architect, had proved the concept. 00:15:35.860 --> 00:15:38.659 You could have a metal frame with a glass skin. 00:15:38.980 --> 00:15:43.500 No more dark, thick -walled fortresses. The building 00:15:43.500 --> 00:15:45.519 could be light, it could be airy, it could be 00:15:45.519 --> 00:15:48.580 transparent. So the Trinity is complete. We have 00:15:48.580 --> 00:15:50.840 the steel frame to hold it up, the glass curtain 00:15:50.840 --> 00:15:53.139 wall to let light in, and the safety elevator 00:15:53.139 --> 00:15:55.539 to get us to the top. The stage is officially 00:15:55.539 --> 00:15:57.940 set. The ingredients are all there. Now you just 00:15:57.940 --> 00:16:00.620 need the ambition. And the ego. And, yes, always 00:16:00.620 --> 00:16:02.919 the ego. Which brings us to the great rivalry 00:16:02.919 --> 00:16:05.620 between New York and Chicago in the late 19th 00:16:05.620 --> 00:16:07.919 and early 20th centuries. This was the Golden 00:16:07.919 --> 00:16:10.480 Age. It really was a tale of two very different 00:16:10.480 --> 00:16:13.100 philosophies. You had the Chicago School, led 00:16:13.100 --> 00:16:15.179 by architects like Louis Sullivan and Daniel 00:16:15.179 --> 00:16:17.580 Burnham. They were obsessed with the logic of 00:16:17.580 --> 00:16:20.059 the steel frame. They believed form should follow 00:16:20.059 --> 00:16:22.220 function. Right. This is Sullivan's famous quote. 00:16:22.259 --> 00:16:24.360 He said, a tall building must be every inch a 00:16:24.360 --> 00:16:27.629 proud and soaring thing. Exactly. He wanted to 00:16:27.629 --> 00:16:29.889 emphasize the verticality. He didn't want it 00:16:29.889 --> 00:16:31.929 to look like a classical column with a base, 00:16:31.950 --> 00:16:33.830 a middle, and a top. He didn't want it to look 00:16:33.830 --> 00:16:36.110 like a layer cake. He wanted to celebrate the 00:16:36.110 --> 00:16:38.590 sheer height that the steel frame made possible. 00:16:38.809 --> 00:16:41.769 But New York. New York had other ideas. New York 00:16:41.769 --> 00:16:44.889 was just feral. New York was pure, uncut capitalism 00:16:44.889 --> 00:16:47.429 and spectacle. It became a literal, publicly 00:16:47.429 --> 00:16:50.629 waged race for the title of world's tallest building. 00:16:50.889 --> 00:16:54.070 And the absolute climax of this era was the insane 00:16:54.070 --> 00:16:56.870 battle between 40 Wall Street and the Chrysler 00:16:56.870 --> 00:17:01.129 Building in 1929 and 1930. This story is wild. 00:17:01.350 --> 00:17:04.490 You had the architect of 40 Wall Street, H. Craig 00:17:04.490 --> 00:17:06.289 Severance, and the architect of the Chrysler 00:17:06.289 --> 00:17:08.720 Building, William Van Alen. And they used to 00:17:08.720 --> 00:17:10.339 be partners, right? They were former partners 00:17:10.339 --> 00:17:12.619 turned bitter, bitter rivals. It was incredibly 00:17:12.619 --> 00:17:15.299 personal. So Severance finishes 40 Wall Street, 00:17:15.380 --> 00:17:17.279 and it's officially taller than the previous 00:17:17.279 --> 00:17:20.180 record holder, the Woolworth Building. He declares 00:17:20.180 --> 00:17:22.720 victory. He thinks he's won. He'd seen the public 00:17:22.720 --> 00:17:24.339 plans for the Chrysler Building and calculated 00:17:24.339 --> 00:17:26.599 that his building was taller, but Van Halen had 00:17:26.599 --> 00:17:28.700 pulled a fast one. He was hiding his secret weapon, 00:17:28.839 --> 00:17:31.539 a trump card. He had been secretly assembling 00:17:31.539 --> 00:17:35.859 a 125 -foot stainless steel spire called the 00:17:35.859 --> 00:17:39.099 Vertex in sections inside the fire shaft of the 00:17:39.099 --> 00:17:41.759 Chrysler building. Nobody on the outside knew 00:17:41.759 --> 00:17:44.799 it was there. So he was basically building a 00:17:44.799 --> 00:17:47.079 cathedral spire inside the building's chimney. 00:17:47.359 --> 00:17:50.619 Effectively, yes. So the day that 40 Wall Street 00:17:50.619 --> 00:17:52.480 is certified as the world's tallest building, 00:17:52.819 --> 00:17:55.880 Van Alen gives the signal. Construction workers 00:17:55.880 --> 00:17:58.160 on the top of the Chrysler building hoisted the 00:17:58.160 --> 00:18:00.460 first piece of this massive spire up through 00:18:00.460 --> 00:18:02.599 the roof and then pieced it all together. In 00:18:02.599 --> 00:18:04.880 the open air. Hundreds of feet above midtown 00:18:04.880 --> 00:18:07.779 Manhattan. In the space of about 90 minutes, 00:18:07.839 --> 00:18:10.880 the Chrysler building grew by 125 feet and completely 00:18:10.880 --> 00:18:13.180 stole the title. That is the single greatest 00:18:13.180 --> 00:18:16.000 architectural mic drop in history. It truly was. 00:18:16.200 --> 00:18:18.599 But it turned out to be a very short -lived victory. 00:18:18.660 --> 00:18:21.519 Because just a few blocks away, something else 00:18:21.519 --> 00:18:23.700 was rising. Something that would dwarf them both. 00:18:24.349 --> 00:18:26.549 The Empire State Building. And that building 00:18:26.549 --> 00:18:28.990 was just a monster. It was on a completely different 00:18:28.990 --> 00:18:31.869 scale. First building ever to pass 100 floors. 00:18:32.150 --> 00:18:35.170 First building over 1 ,200 feet tall. But what's 00:18:35.170 --> 00:18:37.650 still baffling to modern engineers is the speed 00:18:37.650 --> 00:18:39.829 of its construction. I read this and I couldn't 00:18:39.829 --> 00:18:41.450 believe it. They were building four and a half 00:18:41.450 --> 00:18:44.789 stories a week. A week? It's almost incomprehensible. 00:18:45.269 --> 00:18:48.450 The entire project, from the first steel beam 00:18:48.450 --> 00:18:51.410 to opening day, took just over a year. How is 00:18:51.410 --> 00:18:54.089 that even physically possible? It was a masterpiece 00:18:54.089 --> 00:18:56.869 of logistics, like a military operation. They 00:18:56.869 --> 00:18:59.509 had a miniature railway system on the site to 00:18:59.509 --> 00:19:01.910 move materials. The steel beams would arrive 00:19:01.910 --> 00:19:04.309 by train from the foundries in Pittsburgh, still 00:19:04.309 --> 00:19:06.490 warm to the touch, and they would be hoisted 00:19:06.490 --> 00:19:09.349 and riveted into place within 80 hours of being 00:19:09.349 --> 00:19:11.670 made. And the workers, the famous photos of them. 00:19:11.750 --> 00:19:15.170 You had teams of Mohawk iron workers, the Skywalkers, 00:19:15.170 --> 00:19:17.769 who were completely fearless. You had teams of 00:19:17.769 --> 00:19:20.609 riveters tossing red -hot metal bolts. to each 00:19:20.609 --> 00:19:23.029 other, hundreds of feet in the air. It was incredibly 00:19:23.029 --> 00:19:25.170 dangerous, it was deafeningly loud, and it was 00:19:25.170 --> 00:19:27.869 unbelievably efficient. And it opened in 1931 00:19:27.869 --> 00:19:30.329 in the depths of the Great Depression and just 00:19:30.329 --> 00:19:33.009 absolutely crushed all the competition. It held 00:19:33.009 --> 00:19:37.069 the world record for 40 years. 40. That is an 00:19:37.069 --> 00:19:39.549 unprecedented length of time in the skyscraper 00:19:39.549 --> 00:19:43.240 game. Nothing came close. But then... There's 00:19:43.240 --> 00:19:46.500 a long silence. The Great Depression hits, then 00:19:46.500 --> 00:19:49.500 World War II. We basically stopped building giants 00:19:49.500 --> 00:19:52.099 for a couple of decades. The economics just weren't 00:19:52.099 --> 00:19:54.299 there. But when we started to get ambitious again 00:19:54.299 --> 00:19:57.420 in the 1960s, the engineering logic of the simple 00:19:57.420 --> 00:20:00.180 steel frame, the kind used in the Empire State 00:20:00.180 --> 00:20:02.519 Building, hit a brand new wall. So we're back 00:20:02.519 --> 00:20:04.880 to bottlenecks again. We are. You see, the Empire 00:20:04.880 --> 00:20:07.960 State Building is a steel frame, but it's a brute 00:20:07.960 --> 00:20:11.400 force. steel frame. It's packed with steel, it's 00:20:11.400 --> 00:20:14.319 incredibly heavy, and by modern standards, over 00:20:14.319 --> 00:20:17.180 -engineered. As you try to go higher, the wind 00:20:17.180 --> 00:20:19.400 forces increase exponentially. Right, the wind 00:20:19.400 --> 00:20:21.539 is worse at the top. Much worse. And to keep 00:20:21.539 --> 00:20:23.599 a traditional frame stiff enough so it doesn't 00:20:23.599 --> 00:20:26.019 sway like a giant metronome in that wind, you 00:20:26.019 --> 00:20:28.799 have to add so much diagonal steel bracing that 00:20:28.799 --> 00:20:31.099 it becomes wildly expensive, and the interior 00:20:31.099 --> 00:20:34.000 columns get so big and so numerous. You lose 00:20:34.000 --> 00:20:36.640 the floor space again. The columns eat the office. 00:20:37.210 --> 00:20:39.410 Exactly. You're back to the Monadnock building 00:20:39.410 --> 00:20:42.650 problem, but with steel instead of brick. By 00:20:42.650 --> 00:20:44.970 the 1960s, it was clear that if you wanted to 00:20:44.970 --> 00:20:47.410 go higher than the Empire State Building, the 00:20:47.410 --> 00:20:50.369 old cage method just wasn't going to work. We 00:20:50.369 --> 00:20:52.829 needed a new paradigm, a new way of thinking 00:20:52.829 --> 00:20:55.990 about the structure itself. Enter the hero of 00:20:55.990 --> 00:20:59.289 our engineering story, Fazlur Rahman Khan. The 00:20:59.289 --> 00:21:02.230 Einstein of structural engineering. He is an 00:21:02.230 --> 00:21:04.609 absolute legend in the field. I have to admit, 00:21:04.690 --> 00:21:07.450 I hadn't heard of him before this research, but 00:21:07.450 --> 00:21:09.589 it seems like he is the single most important 00:21:09.589 --> 00:21:12.190 figure in the history of the modern supertall 00:21:12.190 --> 00:21:15.329 skyscraper. Without a doubt. Kahn was a Bangladeshi 00:21:15.329 --> 00:21:17.430 -American structural engineer working at the 00:21:17.430 --> 00:21:21.009 firm Skidmore, Owings & Merrill, or SOM, in Chicago. 00:21:21.470 --> 00:21:23.609 He looked at the problem of tall buildings and 00:21:23.609 --> 00:21:25.130 realized we were thinking about it all wrong. 00:21:25.309 --> 00:21:26.970 We were trying to make the inside of the building 00:21:26.970 --> 00:21:29.349 stiff with all this cross -bracing. He said, 00:21:29.369 --> 00:21:31.190 why not make the outside of the building stiff? 00:21:31.470 --> 00:21:34.220 This is the tube concept. This is the revolutionary 00:21:34.220 --> 00:21:37.940 tube concept. His analogy was a bamboo stalk. 00:21:38.259 --> 00:21:40.839 It's hollow in the middle, but the skin, the 00:21:40.839 --> 00:21:44.079 exterior, is incredibly rigid and strong. So 00:21:44.079 --> 00:21:46.380 Kahn's idea was to move the primary structural 00:21:46.380 --> 00:21:48.799 columns to the perimeter, the outside edge of 00:21:48.799 --> 00:21:51.140 the building, and space them very, very close 00:21:51.140 --> 00:21:53.660 together. The exterior wall basically becomes 00:21:53.660 --> 00:21:57.599 a hollow, rigid tube. Exactly. And a tube is 00:21:57.599 --> 00:22:00.180 an incredibly efficient shape for resisting lateral 00:22:00.180 --> 00:22:03.349 loads, which is engineers speak for. wind. The 00:22:03.349 --> 00:22:05.809 whole building acts like a giant cantilever beam 00:22:05.809 --> 00:22:08.710 stuck in the ground. And the huge benefit is 00:22:08.710 --> 00:22:10.789 because all the strength is on the perimeter, 00:22:11.009 --> 00:22:13.390 you can clear out the interior. You don't need 00:22:13.390 --> 00:22:15.450 a forest of columns blocking up the valuable 00:22:15.450 --> 00:22:17.950 office space. And he kept iterating on this idea. 00:22:18.109 --> 00:22:20.710 He developed a truss tube with the John Hancock 00:22:20.710 --> 00:22:22.710 Center in Chicago. That's my personal favorite 00:22:22.710 --> 00:22:25.089 skyscraper. It's just so honest. You know those 00:22:25.089 --> 00:22:27.269 giant X braces you see on the outside of the 00:22:27.269 --> 00:22:29.230 Hancock Center? Yeah, I always just assumed that 00:22:29.230 --> 00:22:30.710 was an aesthetic choice, you know, some kind 00:22:30.710 --> 00:22:33.660 of industrial chic look. Not at all. That is 00:22:33.660 --> 00:22:37.339 pure, unadorned structural necessity. Those giant 00:22:37.339 --> 00:22:40.019 X's are the structure. They take the gravity 00:22:40.019 --> 00:22:41.900 loads and the wind loads and they channel them 00:22:41.900 --> 00:22:44.680 down the exterior columns with incredible efficiency. 00:22:45.319 --> 00:22:48.759 It was so efficient, in fact, that the John Hancock 00:22:48.759 --> 00:22:51.519 Center used nearly half the amount of steel per 00:22:51.519 --> 00:22:54.259 square foot compared to a traditional frame building 00:22:54.259 --> 00:22:57.099 of a similar height like the Empire State. Half 00:22:57.099 --> 00:23:00.490 the steel. That's a massive cost saving. That 00:23:00.490 --> 00:23:03.029 makes supertalls economically viable again. It 00:23:03.029 --> 00:23:04.990 completely changed the economics. And then for 00:23:04.990 --> 00:23:07.269 his masterpiece, he came up with the bundled 00:23:07.269 --> 00:23:11.289 tube. This is the Willis Tower, or as we Chicago 00:23:11.289 --> 00:23:13.410 purists will always call it, the Sears Tower. 00:23:13.589 --> 00:23:16.109 The Sears Tower. The concept here is just brilliant. 00:23:16.309 --> 00:23:18.730 Imagine taking nine cigarettes and holding them 00:23:18.730 --> 00:23:21.450 together in a three by three bundle. Individually, 00:23:21.450 --> 00:23:23.269 they're pretty flimsy. You could snap one easily. 00:23:23.450 --> 00:23:25.509 But when you wrap them together, the bundle becomes 00:23:25.509 --> 00:23:28.539 incredibly rigid. Kahn designed the Sears Tower 00:23:28.539 --> 00:23:31.559 as nine separate square structural tubes bundled 00:23:31.559 --> 00:23:33.759 together at the base. And this solved the wind 00:23:33.759 --> 00:23:36.509 stiffness problem. It did, but it also solved 00:23:36.509 --> 00:23:39.069 a huge aesthetic problem. Because the tubes were 00:23:39.069 --> 00:23:40.930 bundled, you could terminate some of them at 00:23:40.930 --> 00:23:43.109 different heights. That's why the Sears Tower 00:23:43.109 --> 00:23:46.890 has that iconic stepped setback look. Before 00:23:46.890 --> 00:23:49.890 Kahn and the bundled tube, skyscrapers were basically 00:23:49.890 --> 00:23:52.269 just boxes. He made it possible for them to be 00:23:52.269 --> 00:23:54.890 sculptures. His work really unlocked the modern 00:23:54.890 --> 00:23:57.609 era of supertalls in Asia and the Middle East, 00:23:57.650 --> 00:24:00.910 didn't it? The Petronas Towers, Taipei 101, the 00:24:00.910 --> 00:24:04.250 Burj Khalifa. They all owe a huge debt to his... 00:24:04.299 --> 00:24:06.700 tube concepts. They are all direct descendants 00:24:06.700 --> 00:24:09.000 of his thinking. He is the father of the modern 00:24:09.000 --> 00:24:11.299 supertall. So the structural problem of gravity 00:24:11.299 --> 00:24:13.940 and wind stiffness is largely solved by the tube. 00:24:14.220 --> 00:24:16.680 But as we get into the modern era of the supertall, 00:24:16.680 --> 00:24:18.859 that's buildings over 300 meters, and now the 00:24:18.859 --> 00:24:21.680 megatall, which is over 600 meters, we run into 00:24:21.680 --> 00:24:24.839 a new, more subtle enemy, the air itself. Wind 00:24:24.839 --> 00:24:26.799 becomes the dominant force you're designing against. 00:24:27.019 --> 00:24:29.099 For these megatall buildings, gravity is the 00:24:29.099 --> 00:24:31.799 easy part. Wind is the monster. And at that height, 00:24:31.880 --> 00:24:34.279 the wind isn't just a steady breeze. It's a turbulent, 00:24:34.319 --> 00:24:37.660 chaotic, and incredibly powerful force. And we 00:24:37.660 --> 00:24:39.779 need to talk about a specific phenomenon here 00:24:39.779 --> 00:24:42.460 called vortex shedding. This sounds like some 00:24:42.460 --> 00:24:45.240 kind of sci -fi technobabble, but it's very real 00:24:45.240 --> 00:24:48.059 physics. It is the one phenomenon that keeps 00:24:48.059 --> 00:24:51.240 structural engineers up at night. When wind hits 00:24:51.240 --> 00:24:54.220 a big, flat surface, like the side of a square 00:24:54.220 --> 00:24:56.579 building, it can't just go through it. It has 00:24:56.579 --> 00:24:59.079 to flow around the sides. As it flows around 00:24:59.079 --> 00:25:01.680 the corners, it creates these little swirls of 00:25:01.680 --> 00:25:04.920 low pressure or vortices on the backside of the 00:25:04.920 --> 00:25:06.799 building. Kind of like the wake behind a boat 00:25:06.799 --> 00:25:09.599 in water. That's a very similar idea. But here's 00:25:09.599 --> 00:25:12.109 the dangerous part. These vortices don't just 00:25:12.109 --> 00:25:15.470 sit there. They detach or shed from the building 00:25:15.470 --> 00:25:18.349 in a very regular alternating pattern. First 00:25:18.349 --> 00:25:20.289 one sheds off the left side, then one off the 00:25:20.289 --> 00:25:22.490 right side, then left, then right. And that creates 00:25:22.490 --> 00:25:25.009 a rhythmic push and pull on the building. Exactly. 00:25:25.009 --> 00:25:27.329 It creates a lateral force that pushes the building 00:25:27.329 --> 00:25:30.049 from side to side. And if that rhythm, that frequency 00:25:30.049 --> 00:25:32.769 of the vortex shedding happens to match the natural 00:25:32.769 --> 00:25:35.250 resonant frequency of the building itself, you 00:25:35.250 --> 00:25:38.009 get resonance. The swaying motion amplifies. 00:25:38.009 --> 00:25:40.190 It gets bigger and bigger and bigger with each 00:25:40.190 --> 00:25:42.740 push. Like pushing a kid on a swing at the exact 00:25:42.740 --> 00:25:45.000 right moment to make them go higher and higher. 00:25:45.299 --> 00:25:47.579 Precisely. And in a building, that can compromise 00:25:47.579 --> 00:25:50.039 the structure or at the very least make everyone 00:25:50.039 --> 00:25:53.099 on the 80th floor incredibly seasick. So how 00:25:53.099 --> 00:25:55.440 do you fight physics? How do you stop this? You 00:25:55.440 --> 00:25:58.059 can't stop it. So you have to trick it. You have 00:25:58.059 --> 00:26:00.160 to confuse the wind. Confuse the wind. How do 00:26:00.160 --> 00:26:01.880 you do that? You break up the pattern. Look at 00:26:01.880 --> 00:26:04.240 the Burj Khalifa, the current tallest building 00:26:04.240 --> 00:26:07.579 in the world. It's not a smooth, straight extrusion. 00:26:07.799 --> 00:26:10.700 It has that distinctive Y shape and it steps 00:26:10.700 --> 00:26:13.819 back in a spiral pattern as it rises. It's constantly 00:26:13.819 --> 00:26:16.559 changing shape. I see. So the wind never encounters 00:26:16.559 --> 00:26:19.299 the same. consistent building shape for very 00:26:19.299 --> 00:26:22.160 long. Precisely. The vortices that form at 200 00:26:22.160 --> 00:26:24.460 meters are a different size and frequency from 00:26:24.460 --> 00:26:26.940 the ones that form at 400 meters. They never 00:26:26.940 --> 00:26:29.980 get a chance to organize into one single coherent 00:26:29.980 --> 00:26:32.779 force that can rock the whole building. You're 00:26:32.779 --> 00:26:34.940 essentially dismantling the wind's attack. It's 00:26:34.940 --> 00:26:37.660 aerodynamic spoiling. And another strategy I've 00:26:37.660 --> 00:26:40.200 seen on some of the newer, skinnier towers is 00:26:40.200 --> 00:26:42.900 just letting the wind go through the building. 00:26:43.119 --> 00:26:46.279 Blow through floors, yeah. You see this in some 00:26:46.279 --> 00:26:48.920 of the new pencil towers in New York and at the 00:26:48.920 --> 00:26:51.240 top of the Shanghai World Financial Center, the 00:26:51.240 --> 00:26:53.720 one that looks like a giant bottle opener. They 00:26:53.720 --> 00:26:56.299 just leave massive multi -story holes in the 00:26:56.299 --> 00:26:58.420 building. It acts like a pressure release valve. 00:26:58.599 --> 00:27:00.480 Instead of fighting the full force of the wind, 00:27:00.559 --> 00:27:02.500 you just let a lot of it pass right through. 00:27:02.720 --> 00:27:04.759 OK, I want to pivot back to the inside of the 00:27:04.759 --> 00:27:06.880 building again for a minute, because as we go 00:27:06.880 --> 00:27:10.019 higher and higher, the Burj Khalifa is 828 meters 00:27:10.019 --> 00:27:13.839 tall. We run into that old problem, the elevator 00:27:13.839 --> 00:27:16.849 conundrum. but on a whole new scale. It's the 00:27:16.849 --> 00:27:20.250 cruel irony of verticality. To build a super 00:27:20.250 --> 00:27:22.509 tall building, you need to house more people 00:27:22.509 --> 00:27:24.589 to pay the rent to justify the enormous cost. 00:27:24.869 --> 00:27:26.990 More people need more elevators to get them to 00:27:26.990 --> 00:27:29.650 their floors efficiently. But elevator shafts 00:27:29.650 --> 00:27:32.069 take up a huge amount of valuable floor space. 00:27:32.650 --> 00:27:34.589 Eventually, you reach theoretical height where 00:27:34.589 --> 00:27:37.230 the entire floor plan is just elevator shafts 00:27:37.230 --> 00:27:39.349 and bathrooms, and there's no office space left 00:27:39.349 --> 00:27:42.390 to rent. The building literally eats itself from 00:27:42.390 --> 00:27:44.970 the inside out. So we had to get creative with 00:27:44.970 --> 00:27:47.890 vertical logistics. And the solution that was 00:27:47.890 --> 00:27:50.089 pioneered in the original World Trade Center 00:27:50.089 --> 00:27:53.009 was... The sky lobby. This is the train station 00:27:53.009 --> 00:27:55.309 analogy, right? It's exactly like a train system. 00:27:55.490 --> 00:27:57.589 You don't have a train that stops at every single 00:27:57.589 --> 00:28:00.269 little town between New York and Chicago. You 00:28:00.269 --> 00:28:03.009 take an express train to a major hub like Chicago. 00:28:03.230 --> 00:28:05.730 That's what a sky lobby is. You get into a high 00:28:05.730 --> 00:28:08.589 speed express elevator at the ground floor that 00:28:08.589 --> 00:28:11.670 skips, say, the first 40 floors and drops you 00:28:11.670 --> 00:28:13.869 off at the sky lobby on floor 41. That's your 00:28:13.869 --> 00:28:15.549 transfer station. That's your transfer station. 00:28:15.869 --> 00:28:18.250 Then you get out and you transfer to a local 00:28:18.250 --> 00:28:21.089 elevator that services just floors. 41 through 00:28:21.089 --> 00:28:24.029 60. why does that actually save space it sounds 00:28:24.029 --> 00:28:27.109 like more elevators ah because you can stack 00:28:27.109 --> 00:28:29.210 the local elevator shafts on top of each other 00:28:29.210 --> 00:28:31.529 the elevator shaft for the local elevator serving 00:28:31.529 --> 00:28:34.269 floors 1 through 20 can have a completely separate 00:28:34.269 --> 00:28:36.869 elevator car and shaft sitting right on top of 00:28:36.869 --> 00:28:40.250 it serving floors 41 through 60. you are using 00:28:40.250 --> 00:28:42.390 the same vertical tunnel in the building's core 00:28:42.390 --> 00:28:45.930 for multiple independent cars That is incredibly 00:28:45.930 --> 00:28:48.269 smart. Yeah. You're doubling or tripling the 00:28:48.269 --> 00:28:50.450 utility of that empty space in the core. And 00:28:50.450 --> 00:28:52.609 then you have even more advanced systems like 00:28:52.609 --> 00:28:54.950 the double deck elevator, which the Petronas 00:28:54.950 --> 00:28:58.450 Towers famously used. It's one car, but with 00:28:58.450 --> 00:29:01.309 two levels. It loads people from the ground floor 00:29:01.309 --> 00:29:04.150 and the mezzanine level at the same time. It 00:29:04.150 --> 00:29:07.150 doubles the capacity per shaft. Though it does 00:29:07.150 --> 00:29:09.910 have that slightly awkward social moment where 00:29:09.910 --> 00:29:12.470 if the guy in the downstairs car holds the door 00:29:12.470 --> 00:29:14.190 for someone, you're stuck waiting in the upstairs 00:29:14.190 --> 00:29:16.670 car. Efficiency always has its social costs. 00:29:17.009 --> 00:29:19.609 Speaking of costs and efficiency, let's talk 00:29:19.609 --> 00:29:21.170 about something I found in the research called 00:29:21.170 --> 00:29:24.109 vanity height. This was a statistic from the 00:29:24.109 --> 00:29:26.369 Council on Tall Buildings that I found both hilarious 00:29:26.369 --> 00:29:29.329 and a little bit depressing. It's the dirty little 00:29:29.329 --> 00:29:32.549 secret of the super tall industry. Vanity height 00:29:32.549 --> 00:29:35.009 is defined as the vertical distance between the 00:29:35.009 --> 00:29:38.670 highest occupiable floor, so the last place a 00:29:38.670 --> 00:29:41.069 human can actually stand and work or live, and 00:29:41.069 --> 00:29:43.569 the absolute architectural top of the building. 00:29:43.710 --> 00:29:46.950 So it's the spire, the antenna, the empty decorative 00:29:46.950 --> 00:29:48.869 crown. It's the part of the building that has 00:29:48.869 --> 00:29:50.950 no function other than to be tall. The decorative 00:29:50.950 --> 00:29:53.710 hat, basically. And in modern super tall buildings, 00:29:53.809 --> 00:29:57.529 the average vanity height is nearly 30%. 30%. 00:29:57.529 --> 00:30:00.109 Are you serious? So if a building is 1 ,000 feet 00:30:00.109 --> 00:30:03.109 tall, 300 feet of that is just empty air and 00:30:03.109 --> 00:30:05.809 steel truss. In the Burj Khalifa, the vanity 00:30:05.809 --> 00:30:09.910 height is 244 meters. That's over 800 feet of 00:30:09.910 --> 00:30:13.160 unoccupied spire. You could fit the entire Eiffel 00:30:13.160 --> 00:30:15.900 Tower inside the empty, non -functional spire 00:30:15.900 --> 00:30:18.180 of the Burj Khalifa. That's insane. It brings 00:30:18.180 --> 00:30:20.119 us right back to those medieval towers in Bologna, 00:30:20.200 --> 00:30:22.019 doesn't it? Yeah. We're not building for usable 00:30:22.019 --> 00:30:25.119 space anymore. We are building purely to break 00:30:25.119 --> 00:30:27.559 a record. It creates a real tension in the purpose 00:30:27.559 --> 00:30:29.839 of these buildings. Are we building them for 00:30:29.839 --> 00:30:32.140 density and efficiency to solve the problem of 00:30:32.140 --> 00:30:34.599 limited land? Or are we building them as national 00:30:34.599 --> 00:30:37.319 monuments and symbols of ego? Because the environmental 00:30:37.319 --> 00:30:39.779 cost of these things is not trivial. That's the 00:30:39.779 --> 00:30:42.029 perfect pivot to the next. part of our deep dive, 00:30:42.130 --> 00:30:44.390 the environmental impact. Because building these 00:30:44.390 --> 00:30:46.869 things requires absolutely massive amounts of 00:30:46.869 --> 00:30:49.630 energy. We call it embodied energy or embodied 00:30:49.630 --> 00:30:52.660 carbon. To make steel, you need blast furnaces 00:30:52.660 --> 00:30:54.740 running at thousands of degrees, burning huge 00:30:54.740 --> 00:30:57.480 amounts of coal. To make cement for concrete, 00:30:57.759 --> 00:31:00.640 you have to heat limestone in a kiln, which releases 00:31:00.640 --> 00:31:03.160 enormous amounts of CO2 as a byproduct of the 00:31:03.160 --> 00:31:06.019 chemical reaction itself. Then you have to transport 00:31:06.019 --> 00:31:08.299 all that heavy material to the site and use more 00:31:08.299 --> 00:31:10.700 energy to pump it a kilometer up into the Kinski. 00:31:11.279 --> 00:31:13.759 The carbon footprint of just the construction 00:31:13.759 --> 00:31:16.500 is enormous. And once it's built, it's not exactly 00:31:16.500 --> 00:31:19.619 a passive green structure, is it? No, you're 00:31:19.619 --> 00:31:20.960 constantly... You're constantly fighting physics. 00:31:21.059 --> 00:31:23.940 You're fighting the stack effect. Hot air rises. 00:31:24.180 --> 00:31:27.000 In a very tall building, the temperature difference 00:31:27.000 --> 00:31:29.200 between the warm inside and the cold outside 00:31:29.200 --> 00:31:32.420 creates massive pressure differentials, turning 00:31:32.420 --> 00:31:34.920 the building into a giant chimney. You'd have 00:31:34.920 --> 00:31:36.920 to constantly pump water up against gravity. 00:31:37.119 --> 00:31:39.140 You have to power elevators. You have to air 00:31:39.140 --> 00:31:41.579 condition a glass box that is often sitting in 00:31:41.579 --> 00:31:43.859 direct sunlight with no shade from other buildings. 00:31:44.039 --> 00:31:46.099 It honestly sounds like an environmental disaster 00:31:46.099 --> 00:31:48.369 when you put it like that. Is there a counter 00:31:48.369 --> 00:31:50.789 argument? What's the pro skyscraper environmental 00:31:50.789 --> 00:31:54.190 case? The argument is density. If you put 10 00:31:54.190 --> 00:31:56.990 ,000 people to work in the Shanghai Tower, that's 00:31:56.990 --> 00:31:59.730 potentially 10 ,000 people who aren't sprawling 00:31:59.730 --> 00:32:02.390 out into the suburbs, paving over farmland. They 00:32:02.390 --> 00:32:04.930 are sharing infrastructure. They aren't all driving 00:32:04.930 --> 00:32:07.069 cars an hour to work. They're taking an elevator. 00:32:07.640 --> 00:32:10.240 So the per capita carbon footprint could be lower 00:32:10.240 --> 00:32:12.700 than the suburban alternative. It can be, yes, 00:32:12.880 --> 00:32:15.079 if the building is designed correctly. And we 00:32:15.079 --> 00:32:18.160 are seeing a new generation of green skyscrapers 00:32:18.160 --> 00:32:20.400 that are really tackling these issues head on. 00:32:20.480 --> 00:32:22.500 The Shanghai Tower is a great example. It's basically 00:32:22.500 --> 00:32:24.759 a glass building inside another glass building. 00:32:24.880 --> 00:32:27.599 A double skin like a thermos. Exactly. It creates 00:32:27.599 --> 00:32:30.799 this huge nine story tall buffer zone of air 00:32:30.799 --> 00:32:33.440 that circulates between the inner and outer skin. 00:32:33.640 --> 00:32:36.460 It insulates the building, which massively reduces 00:32:36.460 --> 00:32:39.059 the. cooling, and heating load, the Empire State 00:32:39.059 --> 00:32:41.539 Building of all places actually did a huge green 00:32:41.539 --> 00:32:44.799 retrofit a few years ago. They replaced all 6 00:32:44.799 --> 00:32:47.519 ,500 windows with high -performance units and 00:32:47.519 --> 00:32:49.640 upgraded the insulation. They cut their energy 00:32:49.640 --> 00:32:52.480 use by nearly 40%. So the cutting edge of the 00:32:52.480 --> 00:32:55.480 technology is pivoting from how tall can we possibly 00:32:55.480 --> 00:32:58.559 go to how efficiently can we operate at height. 00:32:58.920 --> 00:33:01.700 It is, which leads us to the most surprising 00:33:01.700 --> 00:33:04.259 and, I think, exciting trend in the future of 00:33:04.259 --> 00:33:06.799 skylines. We might be moving away from concrete 00:33:06.799 --> 00:33:09.019 and steel altogether. We're going back to wood. 00:33:09.140 --> 00:33:12.599 The plyscraper. Now, when I hear wooden skyscraper, 00:33:12.660 --> 00:33:16.519 my brain immediately goes to the Great Fire of 00:33:16.519 --> 00:33:19.839 London. I think of a giant pile of kindling. 00:33:20.319 --> 00:33:23.759 Why on earth would we build a very tall building 00:33:23.759 --> 00:33:26.440 out of something that burns? It's a valid question, 00:33:26.619 --> 00:33:28.720 but this isn't the two by four lumber you get 00:33:28.720 --> 00:33:31.880 at Home Depot. This is a new category of material 00:33:31.880 --> 00:33:34.960 called mass timber, specifically cross laminated 00:33:34.960 --> 00:33:38.859 timber or CLT. They take layers of wood and glue 00:33:38.859 --> 00:33:41.519 them together at 90 degree angles to each other 00:33:41.519 --> 00:33:43.839 under immense pressure. So it's like a kind of 00:33:43.839 --> 00:33:46.200 super engineered high tech plywood. That's a 00:33:46.200 --> 00:33:47.819 good way. think of it. And it has the structural 00:33:47.819 --> 00:33:49.400 strength of concrete, but it's about a quarter 00:33:49.400 --> 00:33:51.440 of the weight. That means you need smaller foundations, 00:33:51.619 --> 00:33:53.799 which saves a lot of carbon right there. But 00:33:53.799 --> 00:33:55.599 the real kicker, and this is the part that surprises 00:33:55.599 --> 00:33:58.259 everyone, is its incredible fire resistance. 00:33:58.700 --> 00:34:00.940 How can a massive piece of wood be fire resistant? 00:34:01.380 --> 00:34:04.220 It's all about mass and charring. If you try 00:34:04.220 --> 00:34:07.200 to light a single thick log on a fire with just 00:34:07.200 --> 00:34:10.079 a match, it won't really burn. It just chars 00:34:10.079 --> 00:34:12.820 on the outside. In a building fire, the outside 00:34:12.820 --> 00:34:16.360 layer of a CLT panel turns to charcoal. And charcoal 00:34:16.360 --> 00:34:19.239 is an excellent insulator. That char layer protects 00:34:19.239 --> 00:34:21.179 the structural core of the wood from the heat. 00:34:21.539 --> 00:34:23.559 Steel, on the other hand, doesn't burn, but it 00:34:23.559 --> 00:34:25.980 loses its strength and starts to buckle and deform 00:34:25.980 --> 00:34:29.420 when it gets hot. That is completely counterintuitive, 00:34:29.420 --> 00:34:31.519 but it makes perfect physical sense when you 00:34:31.519 --> 00:34:33.420 explain it. And from an environmental perspective, 00:34:33.760 --> 00:34:36.679 it's a game changer. Concrete emits a ton of 00:34:36.679 --> 00:34:39.880 carbon when you make it. A tree is carbon. That 00:34:39.880 --> 00:34:43.119 tree spent 50 years sucking CO2 out of the atmosphere, 00:34:43.179 --> 00:34:45.320 and now you are locking that carbon into the 00:34:45.320 --> 00:34:47.760 structure of a building for 100 years. The building 00:34:47.760 --> 00:34:50.300 itself becomes a carbon sink. Are these actually 00:34:50.300 --> 00:34:52.579 being built yet, or is this all just architectural 00:34:52.579 --> 00:34:55.079 renderings and fantasy? Oh, they're being built. 00:34:55.519 --> 00:34:59.000 The tree in Norway is 14 stories tall, made of 00:34:59.000 --> 00:35:02.119 CLT. Brock Commons Tallwood House in Canada is 00:35:02.119 --> 00:35:05.039 18 stories. And there's a serious proposal in 00:35:05.039 --> 00:35:07.179 Tokyo from a major timber company called the 00:35:07.179 --> 00:35:11.320 W350 Project, a 70 -story wooden skyscraper planned 00:35:11.320 --> 00:35:14.539 for the company's 350th anniversary in 2041. 00:35:14.800 --> 00:35:17.610 70 stories. Made of wood. It feels like we're 00:35:17.610 --> 00:35:19.650 coming full circle, doesn't it? Yeah. We started 00:35:19.650 --> 00:35:22.090 with mud and timber in Yemen and Rum because 00:35:22.090 --> 00:35:24.570 that's all we had. We moved to steel and concrete 00:35:24.570 --> 00:35:27.489 to conquer the laws of physics. And now we are 00:35:27.489 --> 00:35:30.090 using high -tech engineered timber to try and 00:35:30.090 --> 00:35:32.380 conquer the carbon cycle. It's a really fascinating 00:35:32.380 --> 00:35:34.760 evolution of purpose. We went from building for 00:35:34.760 --> 00:35:36.519 defense to building for commerce to building 00:35:36.519 --> 00:35:39.400 these ego -driven spires and now maybe to building 00:35:39.400 --> 00:35:42.019 sustainable vertical forests. The skyscraper 00:35:42.019 --> 00:35:43.880 has always been a mirror. It reflects whatever 00:35:43.880 --> 00:35:46.139 our society values most at that point in time. 00:35:46.199 --> 00:35:48.539 First it was safety, then it was commerce, then 00:35:48.539 --> 00:35:51.360 national pride, and now hopefully it's sustainability 00:35:51.360 --> 00:35:54.639 and survival. It really does change how you look 00:35:54.639 --> 00:35:57.329 at a city skyline. The next time I step into 00:35:57.329 --> 00:35:59.630 an elevator, I'm not just going to be impatiently 00:35:59.630 --> 00:36:01.489 waiting for the doors to close. I'm going to 00:36:01.489 --> 00:36:04.449 be thinking, I'm riding on a machine with a safety 00:36:04.449 --> 00:36:08.150 brake from 1853 that completely inverted the 00:36:08.150 --> 00:36:10.829 social hierarchy of the modern world. And you're 00:36:10.829 --> 00:36:13.989 standing inside a hollow tube that was specifically 00:36:13.989 --> 00:36:17.110 shaped to confuse the wind. It's all connected. 00:36:17.789 --> 00:36:20.409 As we wrap up this deep dive, I keep coming back 00:36:20.409 --> 00:36:23.619 to that idea of vanity height. We clearly have 00:36:23.619 --> 00:36:26.340 the technology to build a mile -high tower. We 00:36:26.340 --> 00:36:28.119 could probably start tomorrow if someone had 00:36:28.119 --> 00:36:31.159 the money. But the question is, should we? That 00:36:31.159 --> 00:36:33.280 is the ultimate question, isn't it? Just because 00:36:33.280 --> 00:36:35.360 we can conquer the sky doesn't always mean we 00:36:35.360 --> 00:36:37.960 should. But looking at our history from Rome 00:36:37.960 --> 00:36:40.079 to New York to Tokyo, I have a feeling we're 00:36:40.079 --> 00:36:42.239 not going to stop trying anytime soon. We're 00:36:42.239 --> 00:36:45.239 just hairless apes who really, really like to 00:36:45.239 --> 00:36:47.539 stack things high, after all. Thanks for taking 00:36:47.539 --> 00:36:49.199 this deep dive with us. Stay curious.