Okay, so I want you to imagine you're standing
on a street corner. Let's say, I don't know,
Fifth Avenue and 34th Street in Manhattan. Or
maybe you're deep in the financial district in
Hong Kong with that, you know, that dense human
energy all around you. You just stop walking
for a second. And you tilt your head back to
look at the building right in front of you. And
you keep tilting. You keep tilting. You tilt
your head back until... your neck actually starts
to hurt until you can feel the vertebrae kind
of crunching a little bit. And you're looking
up at this just sheer cliff face of glass and
steel that seems to just disappear somewhere
into the clouds. It's really the defining image
of the modern city, isn't it? But if you stand
there long enough looking up at that angle you
start to realize something a little unsettling.
You realize that you're a biological organism.
You know a soft relatively fragile hairless ape
standing the base of a million ton needle that
is for all intents and purposes balancing on
a pinhead. A needle that's actively fighting
gravity fighting the wind every second of the
day and it's housing thousands of other hairless
apes. And yet, what do we do? We walk inside,
we press a button, we shoot up 100 floors to
go grab a latte, and we don't even blink. We've
completely normalized what is objectively an
impossible feat of engineering. That is exactly
what we're doing today. We are stripping back
the skin of the city to do a deep dive into the
skyscraper. And I want to be really clear about
our mission here. This isn't just going to be
a list of the top 10 tallest buildings. We're
not doing the tourist tour. No, absolutely not.
We're looking for the engineering breakthroughs.
We really want to dig in and identify the specific
mechanical and physical problems that had to
be solved. The bottlenecks that basically stopped
us for. Thousands of years. And the aha moments.
And the aha moments, exactly. The flashes of
genius that finally allowed us to, you know,
live and work in the clouds. We're going to talk
about the transition from, say, mud brick towers
in the middle of the desert to these modern tube
structures. these crazy aerodynamic damping systems
that are letting us break the kilometer mark.
We've got a whole stack of source material here,
architectural histories, engineering journals,
even some physics breakdowns of wind vortices.
And what's so fascinating when you look at it
all together is that the history of the skyscraper
isn't this clean, straight line of progress.
It wasn't just, oh, we got better at building.
It was a series of hard stops. Physics would
throw a problem at us, we'd get stuck for a few
centuries, and then someone... somewhere would
have a truly genius idea. So let's start at the
very beginning, or I guess let's start with the
ground rules for what we're even talking about.
Because when I first started reading through
this, the first thing I thought was, okay, the
Great Pyramid of Giza, that was the tallest man
-made thing on Earth for, what, almost 4 ,000
years? It was, yeah. It stands at 146 meters,
which is nearly 500 feet. That is a massive,
massive structure by any measure. But according
to all the experts, it doesn't count as a skyscraper.
It does not. Why not? I mean, it's tall, it's
manmade, it's iconic. What's the missing ingredient?
It's a tomb. I mean, the technical definition
of a skyscraper, if we look at the standards
set by the Council on Tall Buildings and Urban
Habitat, which is kind of the official governing
body for these things, it all hinges on one critical
word, habitability. So you have to be able to
actually live inside it or work inside it. You
have to be able to occupy it, yeah. A skyscraper
is fundamentally a machine for human occupation.
The Great Pyramid, on the other hand, is a solid
pile of limestone blocks with just a few very,
very narrow, very claustrophobic tunnels leading
to a burial chamber. The structural logic is
simple. You just pile rocks until you reach a
point. Okay, that makes sense. The Eiffel Tower
is another great example of this. When it was
built in 1889, it just blew everyone's mind.
It was the first structure to cross that 300
-meter mark, which was a huge psychological barrier.
But you can't live in it. It's the lightest tower.
Exactly. It's an open framework of iron. You
can't rent an apartment in one of the girders.
You can't have an office on the 50th floor because
there is no 50th floor. There's just air and
iron beams. So the real engineering challenge
isn't just make something tall. It's make it
tall, make it hollow, and then fill that hollow
space with heavy people, furniture, plumbing,
partition walls, everything. Precisely. You're
stacking usable, rentable volume. not just stacking
mass. And that distinction is what makes the
history so interesting, because the desire to
do this, to stack families on top of each other,
is actually ancient. Right. This is the common
misconception. I always assumed it was a purely
modern American invention from, you know, the
late 19th century Chicago. That's what most people
think. But the source material points us way,
way back to imperial Rome. Rome. They have villas
and forums, not high rises. Well, Rome had a
serious population crisis. They were constrained
by the city walls. Land was incredibly expensive
and they couldn't just sprawl outward. So what
was the logical solution? They went up. They
developed these apartment blocks called insulae.
And these weren't just like two story townhouses.
Oh, no. These were high rises. We have written
records from people like the poet Marshall and
the satirist Juvenal describing them reaching
10 stories or even more. stories in ancient Rome.
How do you even build a 10 -story building without
steel beams or reinforced concrete? Poorly, to
be honest, very, very poorly. They used a combination
of timber frames, sun -dried mud bricks, and
a kind of primitive rubble concrete. The engineering
was, frankly, terrifying. I'm picturing something
pretty unstable. You're right, too. They were
basically stacking heavy, brittle materials on
top of each other without a proper rigid frame
to hold it all together. The structural integrity
was, let's say, suspect. Suspect is a gentle
word for it, I imagine. It's putting it mildly.
The poet Juvenal actually wrote about what it
was like to walk through the streets of Rome
in constant fear. And he wasn't afraid of muggers.
He was afraid that a pot would fall off a high
ledge and crack his skull. Or worse, that an
entire building would just collapse into the
street. And that actually happened. It happened
all the time. There were notorious fire traps,
too, because they were packed with timber. A
fire could take out an entire block. It got so
bad that the emperors had to step in, right?
The government had to regulate this. They did.
Emperor Augustus set a height limit of about
20 to 25 meters. That's roughly 80 feet, maybe
seven stories. And it wasn't an aesthetic choice
to protect the view of the Forum. It was a public
safety measure to stop the death toll. It's probably
the first example in history of zoning laws being
driven by repeated catastrophic structural failure.
So the ambition, the economic driver to build
high was there, but the material science just
completely failed them. It couldn't keep up.
Now, if we jump forward a thousand years or so
to the Middle Ages, we see another fascinating
attempt in Bologna, Italy. I've seen the old
drawings of this. It looks like something straight
out of a fantasy novel. Yeah, the whole city
skyline is just towers. It really does. In the
12th century, Bologna's skyline looked like a
pincushion. It was absolutely bristling with
these tall, slender towers. The wealthy families
built them as status symbols and for defense.
At its peak, there were somewhere between 80
and 100 of them. And some of them were seriously
tall, right? Like modern building tall? Oh, yeah.
The Asinelli Tower, which is still standing today,
is 97 .2 meters tall. That is nearly a modern
30 -story building. Wow. But again, these weren't
really efficient skyscrapers in the modern sense.
No, not at all. Because they were built with
masonry, the walls had to be incredibly thick
at the base to support that height. So the rooms
inside were tiny, dark, and cramped. They were
built primarily for defense and status. Basically,
my family is more powerful than yours because
my tower is taller, not for maximizing rentable
square footage. It was a medieval measuring contest,
basically. Very much so. But if you want to find
the true ancestral home of the modern skyscraper
city, place that actually functioned like a vertical,
high -density neighborhood, you have to look
at a really unexpected place. Yemen. Shabam.
I've read about this. They call it the Manhattan
of the desert. This place is absolutely incredible.
It dates all the way back to the 16th century.
It's a walled city built in the middle of a desert
wadi, a river valley. To protect themselves from
Bedouin raids, they couldn't spread out. So again,
they went up. And they built these tower houses
out of what? Mud? Sun -dried mud bricks. They
rise 5 to 11 stories high. 11 stories made of
mud bricks. That seems impossible. And they're
still standing today, hundreds of years later.
Now they require constant maintenance. You have
to reapply layers of mud plaster because of rain
erosion, but they function as high density vertical
housing. Each floor of a tower house serves a
different function for the family that lives
there. It's definitive proof that the skyscraper
isn't a technology. It's an economic solution
to a scarcity of land. OK, so we've established
the motivation has been there for centuries.
Rome, Bologna, 16th century Yemen. So why did
it take until the late 1800s for... us to really
break through and build the cities we see today.
What were the hard physical limits? There were
two absolute bottlenecks. One was structural
and the other was, for lack of a better word,
physiological. Let's tackle the structural one
first. The source material calls this the masonry
problem. Right. In all traditional construction,
from the pyramids to those towers in Bologna,
the walls are load -bearing. That means the wall
itself supports the weight of the floor above
it, which supports the wall above that, and so
on all the way up. The entire weight of the building
is channeled down through the walls. So the higher
you go... the heavier the building gets. Exponentially
heavier. And as it gets heavier, the walls at
the bottom have to get thicker and thicker to
avoid being literally crutched under the compressive
load. It's that pyramid principle again. And
eventually you just hit a point of diminishing
returns where it doesn't make sense anymore.
You do. And that practical limit was reached
in Chicago with the Monadnock building, which
was completed in 1891. It's 16 stories tall,
which was absolutely massive for its time. But
to support those 16 stories of brick? The load
-bearing walls at the ground floor are six feet
thick. Six feet. That's wider than I am tall.
Six feet of solid masonry. Now imagine you're
a shop owner on the ground floor. You want big,
beautiful display windows to show off your goods.
You want wide open floor space for your customers.
But instead, you have these tiny tunnel -like
entrances and walls that are eating up half of
your rentable area. You literally couldn't go
any higher because the building would eventually
just become a solid brick pyramid at the bottom.
That's the hard structural ceiling. What was
the physiological problem? Stairs. It's that
simple. It's that simple. Before the mid -19th
century, verticality was a punishment. If you
lived on the seventh floor of a tenement building
in, say, 17th century Edinburgh, which also had
high -rises out of necessity, you were almost
certainly destitute. You had to haul your water,
your coal, your groceries, up seven flights of
stairs every single day. So the penthouse wasn't
a luxury item. Far from it. The rich lived on
the first or second floor. The piano nobile,
the noble floor. The poor lived in the garrets
and attics at the very top because it was cheap,
it was hot in the summer, cold in the winter,
and absolutely exhausting to get to. So to get
to the modern skyscraper, we needed to solve
the wall problem and the stair problem. And this
brings us to what the outline calls the technological
trinity. These three key inventions that all
converged between roughly 1850 and 1890 to make
the modern skyline possible. The safety elevator,
the steel frame, and the curtain wall, the holy
trinity of vertical construction. Let's start
with the elevator. We always credit Elisha Otis,
but hoists and lifts existed before him, didn't
they? Oh, sure. Steam -powered hoists were used
for moving cargo in factories and warehouses,
but they were absolute death traps. They were
lifted by a single hemp rope. If that rope snapped
and hemp ropes frayed and snapped all the time,
the... platform just plummeted and whatever was
on it was destroyed. You would never put a human
being on one of those. So what was Otis's great
innovation? Elisha Otis didn't invent the elevator.
He invented the brakes, the failsafe. This is
the famous Crystal Palace demonstration, right?
1853 at the Exhibition of the Industry of All
Nations in New York. It's pure showmanship. He
gets on this hoisting platform, has it raised
high above the crowd. Then he dramatically orders
his assistant to cut the single supporting rope
with an axe. The crowd must have freaked out.
They gasped. They thought they were about to
witness a man plummet to his death. But the rope
is cut and the platform drops just a few inches
and then stops dead with a loud clang. He tips
his hat and says, all safe, gentlemen. All save...
How did it work? It seems like magic. It was
a brilliantly simple mechanical solution. He
used a large leaf spring mechanism at the top
of the elevator car. While there was tension
on the rope as it was pulling the car up, that
tension held the spring in a compressed state.
But the moment the rope was cut, the tension
vanished. The spring was released and it snapped
outward. And it grabbed onto something. It engaged
these heavy -duty ratchets like big metal teeth
that physically clawed into the guide rails on
either side of the elevator shaft. The system
works because the main rope fails. It's a true
fail -safe. And that one demonstration completely
changed real estate economics forever. Overnight.
The upper floors went from being the least desirable
to the most desirable. You got better light.
You got cleaner air away from the horse manure
and noise of the street. You got the incredible
views. The entire concept of the penthouse was
born the moment Elisha Otis cut that rope. OK,
so now we can get people up there safely. Problem
one is solved, but we still have the six foot
thick walls. We need to get rid of the masonry
problem. And this is where the Industrial Revolution
provides the other key ingredient, steel. We
move from building with stone, which is fantastic
in compression, but terrible in tension. It cracks
if you pull it. To steel, which can handle both
forces beautifully. Exactly. But the real architectural
breakthrough wasn't just the material. It was
shifting the entire load path of the building.
In 1885, an architect in Chicago named William
LeBaron Jenny was designing the home insurance
building. And he had a radical realization. Instead
of stacking heavy bricks, why not build a rigid
cage first? A skeleton. A skeleton. A three -dimensional
grid of iron and later steel columns and horizontal
beams, all bolted or riveted together. This cage,
this internal skeleton, carries the entire weight
of the building. The walls suddenly stopped doing
the heavy lifting. They stopped doing any lifting
at all. Which leads directly to the third innovation,
the curtain wall. I love this term because it
sounds so delicate and decorative, but it really
represents this massive. engineering shift. It
is absolutely radical because the steel frame
is holding the building up. The outer walls are
just hanging off the frame like, well, like curtains.
Their only job is to keep the weather out and
the people in. So you can make them out of anything.
Anything lightweight. You could make them out
of thin panels of stone, terracotta, aluminum.
And this is the crucial part for the 20th century
glass. This is why that building in Liverpool
Oriole Chambers built way back in 1864 is so
important, even though people at the time apparently
hated it. Oh, they despised it. One critic called
it a large agglomeration of protruding plate
glass bubbles. It was hideous to the Victorian
eye, which was used to solid heavy masonry. But
Peter Ellis, the architect, had proved the concept.
You could have a metal frame with a glass skin.
No more dark, thick -walled fortresses. The building
could be light, it could be airy, it could be
transparent. So the Trinity is complete. We have
the steel frame to hold it up, the glass curtain
wall to let light in, and the safety elevator
to get us to the top. The stage is officially
set. The ingredients are all there. Now you just
need the ambition. And the ego. And, yes, always
the ego. Which brings us to the great rivalry
between New York and Chicago in the late 19th
and early 20th centuries. This was the Golden
Age. It really was a tale of two very different
philosophies. You had the Chicago School, led
by architects like Louis Sullivan and Daniel
Burnham. They were obsessed with the logic of
the steel frame. They believed form should follow
function. Right. This is Sullivan's famous quote.
He said, a tall building must be every inch a
proud and soaring thing. Exactly. He wanted to
emphasize the verticality. He didn't want it
to look like a classical column with a base,
a middle, and a top. He didn't want it to look
like a layer cake. He wanted to celebrate the
sheer height that the steel frame made possible.
But New York. New York had other ideas. New York
was just feral. New York was pure, uncut capitalism
and spectacle. It became a literal, publicly
waged race for the title of world's tallest building.
And the absolute climax of this era was the insane
battle between 40 Wall Street and the Chrysler
Building in 1929 and 1930. This story is wild.
You had the architect of 40 Wall Street, H. Craig
Severance, and the architect of the Chrysler
Building, William Van Alen. And they used to
be partners, right? They were former partners
turned bitter, bitter rivals. It was incredibly
personal. So Severance finishes 40 Wall Street,
and it's officially taller than the previous
record holder, the Woolworth Building. He declares
victory. He thinks he's won. He'd seen the public
plans for the Chrysler Building and calculated
that his building was taller, but Van Halen had
pulled a fast one. He was hiding his secret weapon,
a trump card. He had been secretly assembling
a 125 -foot stainless steel spire called the
Vertex in sections inside the fire shaft of the
Chrysler building. Nobody on the outside knew
it was there. So he was basically building a
cathedral spire inside the building's chimney.
Effectively, yes. So the day that 40 Wall Street
is certified as the world's tallest building,
Van Alen gives the signal. Construction workers
on the top of the Chrysler building hoisted the
first piece of this massive spire up through
the roof and then pieced it all together. In
the open air. Hundreds of feet above midtown
Manhattan. In the space of about 90 minutes,
the Chrysler building grew by 125 feet and completely
stole the title. That is the single greatest
architectural mic drop in history. It truly was.
But it turned out to be a very short -lived victory.
Because just a few blocks away, something else
was rising. Something that would dwarf them both.
The Empire State Building. And that building
was just a monster. It was on a completely different
scale. First building ever to pass 100 floors.
First building over 1 ,200 feet tall. But what's
still baffling to modern engineers is the speed
of its construction. I read this and I couldn't
believe it. They were building four and a half
stories a week. A week? It's almost incomprehensible.
The entire project, from the first steel beam
to opening day, took just over a year. How is
that even physically possible? It was a masterpiece
of logistics, like a military operation. They
had a miniature railway system on the site to
move materials. The steel beams would arrive
by train from the foundries in Pittsburgh, still
warm to the touch, and they would be hoisted
and riveted into place within 80 hours of being
made. And the workers, the famous photos of them.
You had teams of Mohawk iron workers, the Skywalkers,
who were completely fearless. You had teams of
riveters tossing red -hot metal bolts. to each
other, hundreds of feet in the air. It was incredibly
dangerous, it was deafeningly loud, and it was
unbelievably efficient. And it opened in 1931
in the depths of the Great Depression and just
absolutely crushed all the competition. It held
the world record for 40 years. 40. That is an
unprecedented length of time in the skyscraper
game. Nothing came close. But then... There's
a long silence. The Great Depression hits, then
World War II. We basically stopped building giants
for a couple of decades. The economics just weren't
there. But when we started to get ambitious again
in the 1960s, the engineering logic of the simple
steel frame, the kind used in the Empire State
Building, hit a brand new wall. So we're back
to bottlenecks again. We are. You see, the Empire
State Building is a steel frame, but it's a brute
force. steel frame. It's packed with steel, it's
incredibly heavy, and by modern standards, over
-engineered. As you try to go higher, the wind
forces increase exponentially. Right, the wind
is worse at the top. Much worse. And to keep
a traditional frame stiff enough so it doesn't
sway like a giant metronome in that wind, you
have to add so much diagonal steel bracing that
it becomes wildly expensive, and the interior
columns get so big and so numerous. You lose
the floor space again. The columns eat the office.
Exactly. You're back to the Monadnock building
problem, but with steel instead of brick. By
the 1960s, it was clear that if you wanted to
go higher than the Empire State Building, the
old cage method just wasn't going to work. We
needed a new paradigm, a new way of thinking
about the structure itself. Enter the hero of
our engineering story, Fazlur Rahman Khan. The
Einstein of structural engineering. He is an
absolute legend in the field. I have to admit,
I hadn't heard of him before this research, but
it seems like he is the single most important
figure in the history of the modern supertall
skyscraper. Without a doubt. Kahn was a Bangladeshi
-American structural engineer working at the
firm Skidmore, Owings & Merrill, or SOM, in Chicago.
He looked at the problem of tall buildings and
realized we were thinking about it all wrong.
We were trying to make the inside of the building
stiff with all this cross -bracing. He said,
why not make the outside of the building stiff?
This is the tube concept. This is the revolutionary
tube concept. His analogy was a bamboo stalk.
It's hollow in the middle, but the skin, the
exterior, is incredibly rigid and strong. So
Kahn's idea was to move the primary structural
columns to the perimeter, the outside edge of
the building, and space them very, very close
together. The exterior wall basically becomes
a hollow, rigid tube. Exactly. And a tube is
an incredibly efficient shape for resisting lateral
loads, which is engineers speak for. wind. The
whole building acts like a giant cantilever beam
stuck in the ground. And the huge benefit is
because all the strength is on the perimeter,
you can clear out the interior. You don't need
a forest of columns blocking up the valuable
office space. And he kept iterating on this idea.
He developed a truss tube with the John Hancock
Center in Chicago. That's my personal favorite
skyscraper. It's just so honest. You know those
giant X braces you see on the outside of the
Hancock Center? Yeah, I always just assumed that
was an aesthetic choice, you know, some kind
of industrial chic look. Not at all. That is
pure, unadorned structural necessity. Those giant
X's are the structure. They take the gravity
loads and the wind loads and they channel them
down the exterior columns with incredible efficiency.
It was so efficient, in fact, that the John Hancock
Center used nearly half the amount of steel per
square foot compared to a traditional frame building
of a similar height like the Empire State. Half
the steel. That's a massive cost saving. That
makes supertalls economically viable again. It
completely changed the economics. And then for
his masterpiece, he came up with the bundled
tube. This is the Willis Tower, or as we Chicago
purists will always call it, the Sears Tower.
The Sears Tower. The concept here is just brilliant.
Imagine taking nine cigarettes and holding them
together in a three by three bundle. Individually,
they're pretty flimsy. You could snap one easily.
But when you wrap them together, the bundle becomes
incredibly rigid. Kahn designed the Sears Tower
as nine separate square structural tubes bundled
together at the base. And this solved the wind
stiffness problem. It did, but it also solved
a huge aesthetic problem. Because the tubes were
bundled, you could terminate some of them at
different heights. That's why the Sears Tower
has that iconic stepped setback look. Before
Kahn and the bundled tube, skyscrapers were basically
just boxes. He made it possible for them to be
sculptures. His work really unlocked the modern
era of supertalls in Asia and the Middle East,
didn't it? The Petronas Towers, Taipei 101, the
Burj Khalifa. They all owe a huge debt to his...
tube concepts. They are all direct descendants
of his thinking. He is the father of the modern
supertall. So the structural problem of gravity
and wind stiffness is largely solved by the tube.
But as we get into the modern era of the supertall,
that's buildings over 300 meters, and now the
megatall, which is over 600 meters, we run into
a new, more subtle enemy, the air itself. Wind
becomes the dominant force you're designing against.
For these megatall buildings, gravity is the
easy part. Wind is the monster. And at that height,
the wind isn't just a steady breeze. It's a turbulent,
chaotic, and incredibly powerful force. And we
need to talk about a specific phenomenon here
called vortex shedding. This sounds like some
kind of sci -fi technobabble, but it's very real
physics. It is the one phenomenon that keeps
structural engineers up at night. When wind hits
a big, flat surface, like the side of a square
building, it can't just go through it. It has
to flow around the sides. As it flows around
the corners, it creates these little swirls of
low pressure or vortices on the backside of the
building. Kind of like the wake behind a boat
in water. That's a very similar idea. But here's
the dangerous part. These vortices don't just
sit there. They detach or shed from the building
in a very regular alternating pattern. First
one sheds off the left side, then one off the
right side, then left, then right. And that creates
a rhythmic push and pull on the building. Exactly.
It creates a lateral force that pushes the building
from side to side. And if that rhythm, that frequency
of the vortex shedding happens to match the natural
resonant frequency of the building itself, you
get resonance. The swaying motion amplifies.
It gets bigger and bigger and bigger with each
push. Like pushing a kid on a swing at the exact
right moment to make them go higher and higher.
Precisely. And in a building, that can compromise
the structure or at the very least make everyone
on the 80th floor incredibly seasick. So how
do you fight physics? How do you stop this? You
can't stop it. So you have to trick it. You have
to confuse the wind. Confuse the wind. How do
you do that? You break up the pattern. Look at
the Burj Khalifa, the current tallest building
in the world. It's not a smooth, straight extrusion.
It has that distinctive Y shape and it steps
back in a spiral pattern as it rises. It's constantly
changing shape. I see. So the wind never encounters
the same. consistent building shape for very
long. Precisely. The vortices that form at 200
meters are a different size and frequency from
the ones that form at 400 meters. They never
get a chance to organize into one single coherent
force that can rock the whole building. You're
essentially dismantling the wind's attack. It's
aerodynamic spoiling. And another strategy I've
seen on some of the newer, skinnier towers is
just letting the wind go through the building.
Blow through floors, yeah. You see this in some
of the new pencil towers in New York and at the
top of the Shanghai World Financial Center, the
one that looks like a giant bottle opener. They
just leave massive multi -story holes in the
building. It acts like a pressure release valve.
Instead of fighting the full force of the wind,
you just let a lot of it pass right through.
OK, I want to pivot back to the inside of the
building again for a minute, because as we go
higher and higher, the Burj Khalifa is 828 meters
tall. We run into that old problem, the elevator
conundrum. but on a whole new scale. It's the
cruel irony of verticality. To build a super
tall building, you need to house more people
to pay the rent to justify the enormous cost.
More people need more elevators to get them to
their floors efficiently. But elevator shafts
take up a huge amount of valuable floor space.
Eventually, you reach theoretical height where
the entire floor plan is just elevator shafts
and bathrooms, and there's no office space left
to rent. The building literally eats itself from
the inside out. So we had to get creative with
vertical logistics. And the solution that was
pioneered in the original World Trade Center
was... The sky lobby. This is the train station
analogy, right? It's exactly like a train system.
You don't have a train that stops at every single
little town between New York and Chicago. You
take an express train to a major hub like Chicago.
That's what a sky lobby is. You get into a high
speed express elevator at the ground floor that
skips, say, the first 40 floors and drops you
off at the sky lobby on floor 41. That's your
transfer station. That's your transfer station.
Then you get out and you transfer to a local
elevator that services just floors. 41 through
60. why does that actually save space it sounds
like more elevators ah because you can stack
the local elevator shafts on top of each other
the elevator shaft for the local elevator serving
floors 1 through 20 can have a completely separate
elevator car and shaft sitting right on top of
it serving floors 41 through 60. you are using
the same vertical tunnel in the building's core
for multiple independent cars That is incredibly
smart. Yeah. You're doubling or tripling the
utility of that empty space in the core. And
then you have even more advanced systems like
the double deck elevator, which the Petronas
Towers famously used. It's one car, but with
two levels. It loads people from the ground floor
and the mezzanine level at the same time. It
doubles the capacity per shaft. Though it does
have that slightly awkward social moment where
if the guy in the downstairs car holds the door
for someone, you're stuck waiting in the upstairs
car. Efficiency always has its social costs.
Speaking of costs and efficiency, let's talk
about something I found in the research called
vanity height. This was a statistic from the
Council on Tall Buildings that I found both hilarious
and a little bit depressing. It's the dirty little
secret of the super tall industry. Vanity height
is defined as the vertical distance between the
highest occupiable floor, so the last place a
human can actually stand and work or live, and
the absolute architectural top of the building.
So it's the spire, the antenna, the empty decorative
crown. It's the part of the building that has
no function other than to be tall. The decorative
hat, basically. And in modern super tall buildings,
the average vanity height is nearly 30%. 30%.
Are you serious? So if a building is 1 ,000 feet
tall, 300 feet of that is just empty air and
steel truss. In the Burj Khalifa, the vanity
height is 244 meters. That's over 800 feet of
unoccupied spire. You could fit the entire Eiffel
Tower inside the empty, non -functional spire
of the Burj Khalifa. That's insane. It brings
us right back to those medieval towers in Bologna,
doesn't it? Yeah. We're not building for usable
space anymore. We are building purely to break
a record. It creates a real tension in the purpose
of these buildings. Are we building them for
density and efficiency to solve the problem of
limited land? Or are we building them as national
monuments and symbols of ego? Because the environmental
cost of these things is not trivial. That's the
perfect pivot to the next. part of our deep dive,
the environmental impact. Because building these
things requires absolutely massive amounts of
energy. We call it embodied energy or embodied
carbon. To make steel, you need blast furnaces
running at thousands of degrees, burning huge
amounts of coal. To make cement for concrete,
you have to heat limestone in a kiln, which releases
enormous amounts of CO2 as a byproduct of the
chemical reaction itself. Then you have to transport
all that heavy material to the site and use more
energy to pump it a kilometer up into the Kinski.
The carbon footprint of just the construction
is enormous. And once it's built, it's not exactly
a passive green structure, is it? No, you're
constantly... You're constantly fighting physics.
You're fighting the stack effect. Hot air rises.
In a very tall building, the temperature difference
between the warm inside and the cold outside
creates massive pressure differentials, turning
the building into a giant chimney. You'd have
to constantly pump water up against gravity.
You have to power elevators. You have to air
condition a glass box that is often sitting in
direct sunlight with no shade from other buildings.
It honestly sounds like an environmental disaster
when you put it like that. Is there a counter
argument? What's the pro skyscraper environmental
case? The argument is density. If you put 10
,000 people to work in the Shanghai Tower, that's
potentially 10 ,000 people who aren't sprawling
out into the suburbs, paving over farmland. They
are sharing infrastructure. They aren't all driving
cars an hour to work. They're taking an elevator.
So the per capita carbon footprint could be lower
than the suburban alternative. It can be, yes,
if the building is designed correctly. And we
are seeing a new generation of green skyscrapers
that are really tackling these issues head on.
The Shanghai Tower is a great example. It's basically
a glass building inside another glass building.
A double skin like a thermos. Exactly. It creates
this huge nine story tall buffer zone of air
that circulates between the inner and outer skin.
It insulates the building, which massively reduces
the. cooling, and heating load, the Empire State
Building of all places actually did a huge green
retrofit a few years ago. They replaced all 6
,500 windows with high -performance units and
upgraded the insulation. They cut their energy
use by nearly 40%. So the cutting edge of the
technology is pivoting from how tall can we possibly
go to how efficiently can we operate at height.
It is, which leads us to the most surprising
and, I think, exciting trend in the future of
skylines. We might be moving away from concrete
and steel altogether. We're going back to wood.
The plyscraper. Now, when I hear wooden skyscraper,
my brain immediately goes to the Great Fire of
London. I think of a giant pile of kindling.
Why on earth would we build a very tall building
out of something that burns? It's a valid question,
but this isn't the two by four lumber you get
at Home Depot. This is a new category of material
called mass timber, specifically cross laminated
timber or CLT. They take layers of wood and glue
them together at 90 degree angles to each other
under immense pressure. So it's like a kind of
super engineered high tech plywood. That's a
good way. think of it. And it has the structural
strength of concrete, but it's about a quarter
of the weight. That means you need smaller foundations,
which saves a lot of carbon right there. But
the real kicker, and this is the part that surprises
everyone, is its incredible fire resistance.
How can a massive piece of wood be fire resistant?
It's all about mass and charring. If you try
to light a single thick log on a fire with just
a match, it won't really burn. It just chars
on the outside. In a building fire, the outside
layer of a CLT panel turns to charcoal. And charcoal
is an excellent insulator. That char layer protects
the structural core of the wood from the heat.
Steel, on the other hand, doesn't burn, but it
loses its strength and starts to buckle and deform
when it gets hot. That is completely counterintuitive,
but it makes perfect physical sense when you
explain it. And from an environmental perspective,
it's a game changer. Concrete emits a ton of
carbon when you make it. A tree is carbon. That
tree spent 50 years sucking CO2 out of the atmosphere,
and now you are locking that carbon into the
structure of a building for 100 years. The building
itself becomes a carbon sink. Are these actually
being built yet, or is this all just architectural
renderings and fantasy? Oh, they're being built.
The tree in Norway is 14 stories tall, made of
CLT. Brock Commons Tallwood House in Canada is
18 stories. And there's a serious proposal in
Tokyo from a major timber company called the
W350 Project, a 70 -story wooden skyscraper planned
for the company's 350th anniversary in 2041.
70 stories. Made of wood. It feels like we're
coming full circle, doesn't it? Yeah. We started
with mud and timber in Yemen and Rum because
that's all we had. We moved to steel and concrete
to conquer the laws of physics. And now we are
using high -tech engineered timber to try and
conquer the carbon cycle. It's a really fascinating
evolution of purpose. We went from building for
defense to building for commerce to building
these ego -driven spires and now maybe to building
sustainable vertical forests. The skyscraper
has always been a mirror. It reflects whatever
our society values most at that point in time.
First it was safety, then it was commerce, then
national pride, and now hopefully it's sustainability
and survival. It really does change how you look
at a city skyline. The next time I step into
an elevator, I'm not just going to be impatiently
waiting for the doors to close. I'm going to
be thinking, I'm riding on a machine with a safety
brake from 1853 that completely inverted the
social hierarchy of the modern world. And you're
standing inside a hollow tube that was specifically
shaped to confuse the wind. It's all connected.
As we wrap up this deep dive, I keep coming back
to that idea of vanity height. We clearly have
the technology to build a mile -high tower. We
could probably start tomorrow if someone had
the money. But the question is, should we? That
is the ultimate question, isn't it? Just because
we can conquer the sky doesn't always mean we
should. But looking at our history from Rome
to New York to Tokyo, I have a feeling we're
not going to stop trying anytime soon. We're
just hairless apes who really, really like to
stack things high, after all. Thanks for taking
this deep dive with us. Stay curious.