Original subtitles

[Jay] How do you crack open an apartment building

and create a man-made canyon inside?

There were moments where I did not think it was going to work,

and I did not think that we would be able to pull it off.

[Jay] What happens when you build

a 630-foot icon...

...without a safety harness?

I honestly didn't know how dangerous it was

until I took my first step up to that platform.

[Jay] And how do you construct dazzling new offices

on a tiny scrap of contaminated land

surrounded by water?

It's impossible, what we've done.

Absolutely impossible.

[serious guitar music]

[Jay] This is the age of the extraordinary.

[Amma] It's totally different from anything around it.

It's like a visitor from another planet.

[dramatic music]

[Jay] Where ingenious engineers

have unleashed unchecked creativity.

Now, their secrets are revealed

as we discover the amazing stories

of their construction.

[Mat] Look at this building,

and your brain just screams at you.

This building does not make sense.

[dramatic choral music]

[Jay] To try and understand...

How did they build that?

If I were to show you a 16-story glass-clad tower

that has a huge canyon carved right through its center,

you'd probably think the folks who designed it were mad,

and you'd be right.

This awesome project in Denver, Colorado,

is the design of Chinese studio MAD Architects.

Seriously, how did they build that?

[dramatic music]

[Jay] The American West's rugged mountains and canyons

have provided inspiration for

authors, filmmakers, and artists.

So, it may be no surprise that in 2019,

they inspired a developer and an architect

to have an incredible dream.

[dramatic music]

[Jay] They decided to build a towering apartment building

in Denver, Colorado that captured the wilderness

in a way never seen before.

It's a piece of amazing theater.

[awe-inspiring music]

The building itself redefines the city.

[Jay] A structure cracked open,

a mountain chasm carved into its side.

The canyon really took elements of the building

and pulled them apart.

[Jay] It was an incredible design

with incredible challenges.

There were moments where it was complete despair.

I did not think it was going to work,

and I did not think that we would be able to pull it off.

[awe-inspiring music]

[Jay] 187 apartments over 16 floors,

with a breath-taking façade.

High-rise living that allows you to walk

straight out into a ravine.

This is One River North.

So...

How'd they build it?

[intriguing music]

[Jay] Denver is set on the high plains

and nestled at the foot of the Rocky Mountains.

[intriguing music]

[Jay] It's a city surrounded by

some of the most spectacular scenery

in the country.

People move here to take advantage of getting out into

its incredible natural surroundings,

hiking, biking, and horse-back riding

on its beautiful trails.

[intriguing music]

[Jay] But, as with many American cities,

Denver is locked in an ongoing battle

with traffic congestion.

Getting out to the mountains isn't always easy.

Developer Kevin Ratner wants to change that.

[Kevin] I think that people are happier in nature.

And I also think that people respond to, uh,

the natural environment in a way that is, uh...

That feels better.

[intriguing music]

[Jay] So, when he snaps up a piece of prime real estate

in the River North district of Denver,

Kevin brings in global architecture firm MAD.

Although they have a history of creating designs

inspired by nature,

such as Suzhou Stadium in China,

this time, they wanna take things much further.

What we really wanted to do is,

we wanted to collapse that distance between

the Rocky Mountains,

and bring the trails, bring the water

to the residence.

I was thinking, "How about you live in the building,

"but you feel yourself living in the natural landscape?

Like a canyon space."

We cut through the structure in different levels.

So, it, it become not only a, a natural garden,

but it's become, uh, a walkable experience.

[intriguing music]

[Jay] To achieve this daring vision,

starting from pile foundations,

a central core will rise up 216 feet

to create 187 apartments across 16 floors.

[intriguing music]

[Jay] It will be wrapped in a beautiful curtain wall,

made up of thousands of individual pieces of glass.

But then, a section will be ripped away

to reveal a fantasy canyon.

Making it a reality will mean finding ways to support floors

that appear to hang in open space.

And figuring out how to sculpt a ravine

in the heart of a 21st-century apartment building.

[intriguing music]

[Jay] It's a bold idea,

and a big gamble for the developers.

[intriguing music]

I thought for sure that there's no way

that they would go for it.

But instead, they, it, they were like, "How," you know,

"how can we not build this project?"

Right?

[exciting music]

[Jay] With the developer committed,

they break ground in summer, 2021.

They dig out 40-foot-deep piles

before beginning to construct the 16-story building.

In a typical apartment building,

you just build a floor and move up to the next.

This one is anything but typical.

When you literally cut into a building,

you're creating massive problems.

To create this organic space was quite a challenge,

because that's, that shape is really irregular

and it goes through all different levels.

[Ed] Each floor was unique.

Each floor had its own geometry, its own design loads and shape.

And so, there was different design at each level.

[serious music]

[Jay] Most often,

floors are supported by regularly placed columns.

But the canyon design makes that impossible.

[Jon] The issue was trying to reduce the number of columns

that came down in the canyon.

'Cause we were really keen on creating a space

where it was immersive.

We really wanted them to feel like they were in nature,

where you didn't feel like you were in

an architectural environment.

And so, that was really the struggle that, uh,

the structural engineer had to deal with.

[Jay] In order to avoid using columns in the canyon,

the engineers turned to a tried and tested engineering trick.

[Ed] The concept, from the beginning

and all the way through,

involved cantilevering that front face.

A cantilever is an overhang that transfers all this weight

into the fixed end down into the foundations.

This allows the floor to project into space.

[Jay] Although the cantilevers allow them to create the canyon,

they now have to deal with the additional forces

they put on the rest of the building.

[serious music]

The stresses get very high around the supports,

and the punching shear stresses

transferring all that heavy load through columns

are a challenge to deal with.

[Jay] These additional loads are creating punching shear,

threatening the stability of the rest of the building.

Punching shear can lead to a building's collapse.

Imagine a slab is a piece of paper,

and a pen is the column.

Put the paper above the pen, push down,

and the pen punctures it.

That's what can happen with a column and a slab.

[dramatic music]

[Jay] How would they prevent this apartment building

from collapsing in on itself?

[intriguing music]

[Jay] In Denver, Colorado,

engineers are battling to create

an extraordinary new apartment building

ripped open by a man-made canyon.

The complex design creates immense forces

where the columns meet the floor slabs,

which could prove to be too much for the structure to bear.

They turn to an ingenious solution.

[Ed] We reinforce all around the column

with something called stud rails,

which is bars that are cast into the slab

that provide the shear reinforcing

around the column.

[Jay] They do this by spreading the pressure

over a wide area of the column.

[serious music]

[Jay] Now the curvy concrete floor slabs can be poured.

Usually a fairly straightforward process,

but not when some of your floors have nothing underneath them

for over 100 feet.

[Ed] Floors do not stack.

There is no structure below to shore off of for construction.

Shoring is when you use temporary props

to support each concrete floor

so that it can be poured and, and held in place

until it dries.

[Ryan] In a typical concrete frame building,

the formwork and reshoring system

is installed across approximately four floors.

In this building,

there were instances in which it was across 9 or 11 floors.

So, two to three times the amount of floors

had reshoring on them during the construction process.

[Jay] At last, by August 2022, the concrete slabs are dry.

Next, it's time to enclose the building

by installing a curtain wall, which will be made up of

over 2700 individual pieces of glass.

[intriguing music]

[Jay] Complicated enough on its own,

the canyon slicing through it creates an enormous headache.

The high quantity of widely-varying shapes and sizes

of the enclosure system

creates a, a challenge for coordination.

[Jay] It's a huge jigsaw puzzle for the team.

Each piece has to be carefully numbered.

Then it takes ten months of precision work

to complete the glass installation.

[serious music]

[Jay] The final challenge is creating

the sculptural surface of the canyon.

How can you recreate

what's taken hundreds of thousands of years

for nature to form?

The canyon itself was a first of its kind for us.

We had never, uh, seen it, much less built it.

[Jay] To make the canyon a reality,

they find inspiration from a surprising source.

[people screaming excitedly]

The same kind of technology that they use to create theme parks

is used to create features here.

[Jay] The system they use is known as chip.

Steel rods are meticulously bet and covered in mesh,

molded to create the canyon.

The backbone of it was prefabricated

and shipped to site in pieces.

[Jay] Once in place, it's coated in plaster.

In total, ten stories of the building

are covered in these plaster sculptures,

slowly forming the canyon.

[Ed] I don't think we felt like it was really coming together

until the plaster and the finishes,

and then, and then it just was...

It just became a really cool reality.

[empowering music]

[Jay] In May 2024, after nearly three years of work,

One River North is ready to welcome its first residents.

Their new homes completely revolutionize

what city living can look like.

The building exceeded my expectations.

When you stand on the seventh floor,

you can look up, and you can see all the way up

through the canyon,

all the way up to the top of the building.

And the first time I walked out there and experienced that,

I was just, I was really just blown away.

[Dr. Mabry] Who wouldn't wanna live close to nature like this?

You don't have to drive for an hour

or take a walk outside of the city.

You've got a canyon walk right outside your front door.

[empowering music]

[Jay] An innovative living landmark

that brings nature and the mountains

to people's doorsteps.

[Monica] It's gorgeous.

It has water flow, it has live trees.

I mean, I don't think there's another building

not only in Denver, but in the US that,

that has that.

[Ryan] I remember driving down the highway

and catching the building out of the corner of my eye,

and it just, it just struck me in,

in a great way,

how significant that canyon was,

and how visible it was gonna be

from so many different points of the city.

[empowering music]

[upbeat percussion music]

Two years before the United States

sent astronauts to the moon,

the city of Saint Louis was sending intrepid sightseers

to the top of the world's largest arch.

But before anyone went upward bound,

a problem had to be solved.

Because of its enormous size,

the arch had to be made in two separate sections.

Its designers would only know for sure

if they got their math right

and if the two sections would actually meet in the middle

when they were raised 630 feet up in the sky.

[intriguing] music]

[Jay] In 1947,

the state of Missouri challenged the architecture world

to design a monument that would honor the spirit

of the western pioneers.

[intriguing music]

[dynamic music]

[Jay] When completed,

it would become one of the most recognizable structures

in the United States.

It's an iconic construction.

It completely changes the skyline.

[Jay] New technology would have to be developed

in order to build it.

[Pam] How do you even build this

when there's no crane that can go 630 feet in the air?

[Jay] But controversial hiring practices

also lead to protests during its construction.

They climbed the arch and handcuffed themselves

to the structure.

[dynamic music]

[Jay] Twenty-eight years later,

it would soar from foundations piled 60 feet underground,

630 feet into the air

to become the tallest monument in the United States...

[dramatic music]

[Jay] ...and the highest arch in the world.

This is the Gateway Arch.

So, how did they build it?

[serious music]

[Jay] Saint Louis, which is almost

the geographical center of the US,

was originally a humble fur-trading post.

And in 1804, its position made it

the perfect jumping-off point for two pioneers,

Lewis and Clark,

as they set out to explore the uncharted West.

[awe-inspiring music]

[Jay] Over the next 100 years, the city grew fast,

with the Mississippi and Missouri rivers

making it the perfect trading route.

But by the early 20th century,

with trading moving to the railroad

and the Great Depression taking its toll,

the city was down on its luck.

[Pam] Saint Louis, at the time,

was facing, like much of the country, a depression.

A lot of people out of work.

The riverfront itself had become a lot of abandoned warehouses

that were falling into disrepair.

[Jay] Saint Louis needed to do something

to turn its fortunes around.

In 1947, they launched an enormous competition

to design an incredible monument

that will celebrate the city's pioneering history

and give it back its sense of pride.

They wanted something that would spark excitement

and interest in the populace,

and become known nationally as well as internationally.

[Jay] There are 172 entrants from across the country.

The winner is Eero Saarinen.

He would go on to create the futuristic TWA Flight Center

in New York's JFK Airport

and the Dulles National Airport outside Washington D.C.

But winning the competition is his first major commission.

Eero Saarinen envisioned something that

represented Saint Louis

as the gateway to the West in a very literal sense.

When you look at the arch,

you can imagine it as a doorway

to these new and unexplored lands.

It really shows the pioneer spirit.

[Jay] His vision is for

a futuristic reimagining of an ancient structure.

An arch built on a scale so vast,

it will pose unprecedented challenges

for the engineers.

First, they will need to create foundations strong enough

to support the weight of the 630-foot-tall arch.

Then, they'll need to figure out

how to build its two towering legs

from individual sections.

The whole plan will rest on careful calculations,

which will only be proved right or wrong

when the two halves of the arch meet in the middle.

If they pull it off,

visitors will be able to take a specially-built tram

up to an observation deck at the top,

creating a magnificent gateway tribute

to the westward expansion of the United States

and its historic pioneers.

The commission is won in 1948.

But it takes another 14 years to pull together the funding

to start work.

On the upside, this gives Saarinen and the team

time to work out how on earth they're gonna build it

in a time before computer-aided design.

Saarinen has to calculate

the total weight of the structure,

the dimensions, the angles, the curves,

the strength of materials...

On and on and on.

It seems almost impossible to us today

that they did this without the benefit of modern computers.

[Jay] At the heart of Saarinen's plan

is a piece of engineering magic.

It's called an inverted catenary curve.

A catenary curve is the shape of a hanging chain

that forms naturally

as a result of gravity pressing along the entire chain.

[Susan] I went down in, into the basement,

and up on the ceiling, um,

were these chains that were hanging.

He was studying the proportions

and what the exact curve ratio should be.

[Jay] Because the forces are distributed

evenly and efficiently,

when one of these hanging curves is inverted,

it becomes incredibly strong.

Just as well when you're building

the nation's tallest monument.

[serious music]

[Jay] In June 1962,

work begins clearing the site.

First, they need to create the foundations.

These footings need to be strong enough

to handle the downward forces

that will be created by the 630-foot arch.

This means using reinforced concrete;

26,000 tons of it.

To make the concrete strong,

they'll need to pour it continuously.

Otherwise, it won't set uniformly.

Truck after truck had to come in,

so it almost had to be like a, a finely-tuned concert

to make sure they got in, dumped their load of concrete,

and moved off so that the next one could come in.

[Jay] Twenty-six hours

and 2,000 trucks of concrete later,

the foundations are poured.

The next major challenge

is making sure the legs are gonna be strong enough

to withstand the arch's weight.

For the solution, the team turns to the humble triangle.

Each section of the arch is created from

three super-strong links of steel welded together.

Equilateral triangles are the strongest shape,

as they distribute forces equally and evenly

across all three sides.

No matter where the force comes from,

you know the structure will not deform.

[Jay] As each piece is completed,

they are welded inside and out, the legs slowly climbing higher.

[serious music]

[calm music]

[Jay] As work progresses,

in July 1964,

the same year the Civil Rights Act

is signed into law,

the arch becomes the focus of not the city's rebirth,

but of racial injustice and discrimination.

Local man Percy Green scales it

to protest about how few African Americans

are working on the project.

His six-hour sit-in is reported across the country.

[Jennifer] This protest actually brought attention

to these unfair hiring practices,

and made a change in federal hiring

with repercussions that echoes today.

[Jay] Although the protest

doesn't improve things immediately,

it helps bring about long-term change.

[serious music]

[Jay] On site, work continues, though it soon hits a problem.

The arch will be so high,

that there isn't a crane tall enough

to finish the building it.

[Jennifer] For the first few sections,

they used regular cranes.

At about 72 feet, they had to switch their plan,

because the crane couldn't reach that high.

[Jay] The solution is to devise something truly extraordinary.

A crane that can climb the arch as its built,

pulled up by rails attached to each leg.

[Barb] They were able to have a crane

actually climb up that rail.

The cranes would be able to

attach steel sections on each leg.

[Jay] It's not long, though, before the team is facing

its next challenge.

The higher up they went, the stronger the winds felt.

There could be gusts of wind that reached

50 or more miles per hour.

[Hayley] Winds create sideways pressure

on a building.

So, you have to factor in additional strength.

But if you make it too rigid,

then the force from the winds could cause structural damage.

[serious music]

[Jay] To counteract the effect of the wind,

the engineers come up with a plan.

Each leg is built with a double-skin steel wall.

Between them, tension cables are run from top to bottom.

These cables are tightened enough to provide stability,

but still allow the legs to move,

absorbing the force of the wind

and preventing it from causing structural damage.

It was designed that it will sway up to 18 inches.

That'd be nine inches either side.

And it's built to withstand up to 150-mile-an-hour winds.

[Jay] Incredibly, the men building it are doing so

hundreds of feet above the ground

in a time where no one wore safety harnesses.

I honestly didn't know how dangerous it was

until I took my first step up to that platform.

I was almost petrified.

It seemed like every time we did something,

there was something scary gonna happen.

It was the first job that I was afraid every single day.

[Dr. Mabry] It's literally insane.

You're working 600 feet up,

facing winds, and focusing on doing your job.

One lapse in concentration, one slip,

you'll be facing certain death.

[Kirk] The insurance companies predicted that

they were gonna have 12 or 13 deaths

during the construction.

They had zero.

[calm music]

[Jay] In October 1965, three years into the build,

they are ready to complete the arch.

It's the moment of truth.

Success all comes down to those two legs meeting in the middle.

If they don't, it's total failure.

[upbeat percussion music]

[awe-inspiring music]

[Jay] In Saint Louis, Missouri,

the team building the Gateway Arch

are holding their breath

as they fit the final section of steel.

And they knew they had to be within 1/32 of an inch

in order to make it all work.

The pressure was on.

After all this time and all this effort,

all these thousands of people working for years,

everything comes down to this one moment.

[Jay] To make things even more difficult...

Fitting the last piece is a race against the clock.

[Jennifer] They knew they had about 45 minutes

before the sun's heat would make it impossible

for the last piece to fit into place.

The sun was warmin' up the south leg enough

to where they would not fit in.

[Jay] With time running out, they call in reinforcements.

[dramatic music]

They had the fire department come in

to start hosin' down the south leg to cool it off

so it opened up enough to drop that final piece in.

[Man] The leg's comin' up, Bill.

[dramatic music]

[Jay] Against the odds...

[dramatic music]

[Jay] ...the arch is complete.

[dramatic music]

[Jay] In June 1967,

five years after construction began,

the magnificent monument opens to the public.

[uplifting music]

[Jay] A specially-built tram hidden inside the legs

is ready to carry over a million people a year

up to a spectacular view overlooking the city.

Saarinen's daughter was one of the first to enjoy it.

The first time I went up the arch,

I looked down at Saint Louis,

and I couldn't believe how emotional I could feel,

um, looking through those little windows.

[awe-inspiring music]

It's a beautiful sight.

It's somethin' to be proud of,

and for me, it's a silver rainbow.

Yeah, a silver rainbow.

[Jay] Its 630 feet of towering triangular steel

elegantly frames historic Saint Louis,

giving the city back its sense of pride.

The Gateway Arch was built to put Saint Louis

back on the map,

and wow, did it do that.

[Ted] This thing is beautiful,

and people still come by the millions to view it.

And that makes me proud.

[empowering music]

[upbeat percussion music]

What do you call a triangular glass office block building

built, constructed on

a contaminated World War II reclaimed plane fuel depot,

which appears to float above a gigantic concrete pedestal

and has stunning views all the way to Sweden?

Soundport. Sounds good.

Yeah, it does, and it looks even better.

[serious music]

[Jay] Copenhagen in Denmark is regularly ranked as

one of Europe's happiest cities

thanks to its clean air, healthy lifestyle,

and great work-life balance.

So, it's no wonder that when one of

the world's biggest pharmaceutical companies

wanted a striking new research and design center,

they chose to build it here.

[dramatic music]

[Jay] Their new home is a gleaming triangular building

that rises up from the Copenhagen waterfront.

It stops you in your tracks.

It looks like the most beautifully designed ship

ready to launch out to sea.

[Jay] Constructing it on this tiny triangular plot, though,

meant overcoming some serious problems.

It was a, a challenging site.

It's an alienated island.

No space around the, uh, building.

[Jay] The land was contaminated,

the ground not strong enough to build on.

It's impossible, what we've done.

Absolutely impossible.

[Jay] Against all odds,

the team created a 360,000-square-foot building

with astonishing views out to sea.

Flooded with light from a dome glass ceiling

made up of 638 individual panes.

This is Soundport.

So, how'd they build it?

[intriguing music]

[Jay] Back in the 1950s,

Ferring was a small Swedish pharmaceutical company

operating out of two rooms.

Fast forward 60 years to the 2010s,

and it's become one of

the biggest pharma names in Scandinavia,

with offices worldwide.

They decide to build a new research and development center

in Denmark.

To do it, they bring in one of the world's

most influential architecture practices,

Foster + Partners,

responsible for the Millau Viaduct in France

and the Gherkin in London.

We're trying to do something for them

that can be really extraordinary.

And to have a client who's trusting you to do something

that they see as really important to them

and the future of their business and also to their history,

that's a real pressure, pressure as a designer.

[Jay] What's more, the client has fallen in love

with a site with wonderful views back over the water

to Sweden, where the company was founded.

But while the views might be good,

the plot is an awkward triangular shape,

and that's only the beginning of its challenges.

[upbeat music]

[Jay] The first problem to solve

will be building a foundation system

that can keep water out

and support the weight of the building

on the waterlogged site.

Then, the design will need to squeeze

as much office space as possible onto the triangular-shaped plot.

That will mean finding clever ways

to support a building that widens as it rises.

[upbeat music]

[Jay] Finally, they'll need to devise a roof structure

that will look both beautiful and give office workers

as much natural light as possible,

even in the dark Danish winters.

[intriguing music]

[serious music]

[Jay] It's September 2016,

and before they can even break ground,

they had their first challenge to overcome.

[serious music]

[Jay] As is happening more and more around the world,

to protect unspoiled countryside,

the plan here is to redevelop land

that's been used in the past.

That's if it can be made safe to build on.

[Andrea] That existing piece of land

was dating back to the Second World War,

and had been used as, uh, chemical storage.

[Jay] During the Second World War,

chemicals were stored here,

and traces still remain in the soil.

You have to take building on

contaminated land very seriously.

[Jay] On this site, that's particularly complicated.

The potential for things going horribly wrong

increases exponentially if you're excavating near water.

Hazardous pollutants leaking into rivers, lakes, the sea,

or groundwater suddenly have the potential to wreak havoc.

[Jay] Not only do they need to make sure no contaminants

leak into the sea and harm marine life...

...but the waterlogged soil isn't strong enough

to support the weight of the huge new building.

The ground is so weak,

that if you tried to build on it,

there's a risk that the plot starts to sink into the sea.

[Jay] They decided to surround the island

with a steel wall hammered into the ground.

This should stop the land from collapsing,

and prevent contaminants from leaking into the sea.

But there's a problem.

Water is still trickling in through the gaps in

the sheet piling.

[Jay] One solution is to send divers in

to weld the sheets underwater.

But the costs are mind-blowing.

It was more or less more than one million.

Uh, extra, extra, extra money.

[Jay] How will they avoid completely blowing their budget?

[percussion music]

[Jay] In Copenhagen, Denmark,

the team tasked with building

a new research and development center

are struggling to stop seawater flooding into the foundations.

Luckily, the project's Italian engineers

come to the rescue.

Our company work many times in Venice.

And in Venice, you are always by the sea.

One thing that we have learned, working in this environment,

was to seal the sheet piling with,

with a mix of cement and wood.

[Jay] The team sprays a blend of concrete and sawdust

along the perimeter of the steel wall.

The tide does the rest,

pulling this into all the gaps, which then seal.

[Dr. Mabry] It's an amazing solution.

That's the best kind of engineering.

The sawdust/cement mix creates kind of a slurry

that's more like clay.

It can mold itself and better fit in and seal gaps.

An ingenious idea that saved millions of dollars.

[Jay] With the island sealed from the sea,

in December 2017,

they begin the job of creating the foundations

and making the site safe from the contaminated soil.

The strategy they chose to fix it is called capping.

Essentially, it's sealing the whole site in concrete.

[Jay] It's a simple solution,

but one that involves pouring 7,800 cubic yards of concrete.

Now, they're finally ready to start working on

the building itself.

[serious music]

[Jay] To fit enough office space onto the tiny spit of island,

the building needs to be bigger than the plot.

The architects have cleverly designed it

to get wider as it rises,

with each floor larger than the one underneath.

The trouble is supporting the floors during construction

takes an extraordinary amount of scaffolding.

It was pretty impacting to see the west corner

as it was being built,

as the scaffolding and the necessary props were added.

In the end, it was certainly a project within the project.

[Jay] The next challenge is devising a way of

holding up these floors permanently.

The client doesn't want the look of the building spoiled

with a lot of columns.

Instead, they come up with an ingenious solution.

Hidden further back in the building

are giant concrete cores,

supporting chunky horizontal trusses.

Steel rods will hang from these

to support the floors from above.

[serious music]

[Jay] Before the scaffolding can be removed,

the rods must be tightened

to create the precise amount of tension needed

to hold the floors' weight.

They have to carefully adjust each of the bolts,

securing each rod in turn,

monitoring the tension the entire time.

[Jay] If the rods end up too taut or too slack,

there's a danger the floors will crack or even collapse.

It's a tense moment for the team,

led by Pietro Boerio.

I was obviously on the top of the building, of the floor

when, when, uh, we, uh, we make the tensioning.

Because...

Like...

the, the captain of the ship, when the ship go down,

the captain go down, no?

The same! I was at the top of the building.

[Jay] Thankfully, all goes the plan.

And with the rods successfully tightened,

the build continues.

The next challenge the team faces

is making sure the building lets in enough light.

In winter, Copenhagen can get

as little as seven hours of daylight.

A problem that Danish building rules

take very seriously.

There's a lot of regulations, uh, like in many countries.

But for, for Denmark, I, I find them maybe a little bit tougher.

[David] It means, effectively,

that every desk has to have a minimum daylight on it,

and every worker at a desk needs to have daylight and views.

What it means is you can't have a desk

more than six meters away from a window.

[Jay] It's easy to get light along the edges of the building

by glazing the external walls.

But it's a challenge bringing it to the center,

particularly with the low winter sun.

The solution is an atrium, but not any old atrium.

So, atriums don't let in very much daylight.

If we're gonna do an atrium,

we have to reoptimize its potential to,

to let in as much daylight as possible.

[Jay] Whatever they build needs to cover an area

of 17,000 square feet.

That's a lot of glass and a lot of weight to support.

[David] If you put a beam across,

it would be over two meters deep.

So, obviously that's not going to work

and give you the kind of transparency.

[Jay] Luckily, the architects are experts

when it comes to beautiful glass roofs.

In 2000, Foster + Partners

covered the British Museum in London

with a structure known as gridshell.

Like an egg,

a gridshell's curved shape makes it very strong,

which means it can have the least amount of structure

with the most amount of glass.

The simplest way to make one

is to stitch together a lot of flat triangles.

They are simple shapes,

and can more easily tile complex surfaces

without needing to bend,

as any three points of the triangle

can lie flat on a curved surface.

[Jay] This time, though,

they wanna let even more light in

by reducing the amount of steel and creating bigger panes.

To do it, they decided to make their gridshell

using four-sided shapes, or quadrangles.

But that brings with it the next major challenge.

For a quadrangle to adapt to a curved surface,

at least one of its sides needs to bend.

[Jay] Traditionally, bent glass would have to be

manufactured using heat.

Making the vast number of different-shaped pieces

required for a roof as complex as this

would be expensive and energy intensive.

So, they turn to a pioneering method

called cold bending.

[David] Cold bending,

you're effectively mechanically pushing it down on,

in, in situ.

[Jay] Because it can be done on site,

it's much cheaper.

But forcing such a delicate material to bend

requires painstaking planning.

[David] So, glass has

an inherent bending capacity in it,

but there's a limit to how much it bends until it fails.

So, it's really understanding that point.

What is the maximum limit?

[Jay] Having carefully calculated

exactly how much pressure the glass can take,

638 individual flat glass panels

are carefully screwed into the curved frame,

bending as they adapt to its shape.

It takes 8,100 clamps and more than 16,000 screws,

but at last, the roof is complete.

[serious music]

[Jay] In October 2022,

Soundport opens its doors for business.

[dynamic music]

[Jay] It's taken 33,000 cubic yards of concrete,

4,700 tons of steel,

and nine years to get here.

But now, it stands firm,

looking out across the water to Sweden.

As a piece of architecture, I think it's very, very good.

[David] Many people who visit the building

are very surprised between the outside and the inside.

It's completely unexpected

when they walk into that atrium space.

[Mat] This is a dream breathed from a plan.

Make the most of these great views on the water,

and make sure the building's stunning.

[serious music]

[dramatic music]

[dramatic choral music]