Original subtitles

Narrator: How does this incredible skyscraper

defy the laws of physics?

Man: This house always is on the verge of falling down.

Narrator: What happens when one of the world's richest men

and its most extreme architect

create the impossible?

Man: Obviously we know that levitation of buildings

hasn't been invented yet.

Narrator: And how do you build a 1,000-foot-high elevator

in an area so remote,

heavy machinery can't be used?

This is the age of the extraordinary...

Man: Where else can you swim from one skyscraper to the other

300 feet in the air?

Narrator: Where ingenious engineers

have unleashed unchecked creativity...

Woman: Everything in this building

pushes at the boundaries of what's possible.

Narrator: Building structures so outrageous,

they defy logic.

Woman: The forces on this thing

look like it should be torn apart.

Narrator: Now their secrets revealed.

Discovering the incredible stories of their construction...

Woman: These are extraordinary feats of engineering.

Narrator: To try and understand

how did they build that?

New York's Manhattan island,

where the skyscraper rules the roost.

Ever since the first one went up over a century ago,

the drive has been to push towers taller and cheaper.

But the resulting demands on engineers

have created repetitive, predictable shapes.

Creative flair and groundbreaking design

were rare exceptions.

That was until 2017,

when in Manhattan's Tribeca district,

a spectacular new tower was unveiled.

This is 56 Leonard street,

where a team of engineers and architects

stepped over the cutting edge,

ripping up the skyscraper rule book.

Woman: The shapes are extraordinary...

Boxes stacked on one another.

And some of them are slid out.

The whole thing looks so precarious.

Narrator: At Leonard street,

56 stories of unique apartments

are stacked ever more daringly right up to its 820-foot summit.

Here at the top,

engineering logic seems to have been recalibrated

to defy the laws of gravity.

Woman: It all just looks a bit scary.

Narrator: Unique apartments with sky-high impossible overhangs

created a complex and expensive construction.

So, how did they build it?

Even more than most cities,

Manhattan is space-hungry,

resulting in tall buildings with simple layouts

that are a compromise between the engineering challenge

of building a skyscraper

and the practical economics of doing it at a price.

Nehemiah mabry: Most skyscrapers and tall buildings

are either rectangular or tubular

because those are really efficient shapes

when it comes to supporting themselves.

Joshua macabuag: For construction purposes,

developers like to have buildings be fairly regular

and columns going straight down, et cetera,

@so that every floor is the same

and they can just build it nice and quickly.

Narrator: These uniform layouts are now so efficient to build

that a conventional high-rise with over 50 floors

can be completed in just weeks.

But the results are often a little underwhelming.

Woman: Imagine, you wanted to change things up a bit.

Ellie cosgrave: You could put this cantilevered section

in there...

This box section in there.

And you might want to even like take out bits...

Oops.

Narrator: Changing it up

in the world of skyscraper construction

means taking risks.

But that wasn't going to stop developer izak senbahar.

Izak senbahar: We knew this was gonna be a very tall structure

and very visible from almost every angle in the city.

So we said, ok,

we have a responsibility to do something iconic.

We didn't want something repetitive,

some just straight up building.

We wanted something more interesting,

more sculptured.

Narrator: When izak bought the site in 2008,

Tribeca was not one of Manhattan's

glamorous residential districts.

But building something special anywhere in New York

is expensive,

so these apartments would have to command top dollar.

Needing a design that would attract the uber rich,

izak headed to Europe

and world-renowned Swiss architects

herzog & De meuron.

Jacques herzog: We felt that izak was ready

for a new approach,

a more radical approach.

Narrator: Herzog & De meuron's portfolio

includes some truly incredible buildings,

like bayern Munich's arena stadium

and London's Tate modern extension.

But no skyscrapers.

Jacques: Even if we had done a building before,

a tall building,

we would always look at it from a different angle

and would give him something unexpected.

We want it to be a stack of apartments

but not an anonymous one.

The building could be understood as a pile of individual pieces,

even in the middle part,

and then the top,

which would have even more exclusive apartments

which we decided could become like stacked private homes.

And I think that's really new

and hadn't been done before anywhere.

Narrator: There's good reason it's never been done before.

In order to make a strong, stable building,

irregular spaces are normally built

into the super stable lower floors,

with smaller structures at the top.

The architect concept that the higher the apartments are,

the more off-balance they appear,

flipped conventional high-rise engineering on its head.

To pull this trick off at the top,

they needed to reduce

structural complexity lower down,

while still making the floors appear to be different.

To do this, they hatched an ingenious plan.

The first 46 floors would be built in the conventional way,

using continuous outer columns and inner walls

to provide support for the floors above.

The floor layouts would also repeat,

but they'd be made to appear different

by changing the size and position of balconies and edges.

The 46th floor would be unoccupied

and so could be packed with load-bearing walls,

creating a 47th floor plate

that would be super-strong, super-stable platform.

Skyscraper specialist hezi mena

was the structural engineer tasked with making it happen.

Hezi mena: We tried to stiffen up the building enough

up to the 46th floor.

So when we reach the 47th floor,

the first sky villa,

the building will have sufficient stiffness

@that we can have the flexibility

of doing whatever we want structurally

and give the architect the freedom

to do whatever he wants with the space.

Narrator: And what the architects wanted

was to create an extraordinary visual effect.

Jacques: If you make this upper box,

let's say, hover to a certain degree,

you don't make it hover so it collapses.

You can push it to an extreme, you know,

like in chaplin's movie, you know,

where this house always is on the verge of falling down.

Together with the structural engineer,

you find the right moment between something fragile,

something even dangerous.

Narrator: The vision for off-balance apartments

that still had wraparound views

meant pushing structural concrete engineering

right to the edge.

The lower floors

used conventional skyscraper engineering,

where continuous columns share the load.

But because the top nine floors are all offset,

that same system wouldn't work.

Each of these floors has to be stiff enough

to support huge cantilevered overhangs,

some over 23 feet.

And they had to do that

without compromising the view from within.

To pull it off,

engineers turned to a 125-year-old idea...

The vierendeel truss.

A regular truss uses diagonal cross members

to create triangles

that make it very strong both laterally and vertically.

But the views from within would be ruined.

A vierendeel truss

connects the two floors using only vertical columns.

So it's just as strong vertically

and it keeps its lateral strength

through the massively strong central lift shaft column

that also connects the floors.

So the vierendeel truss allows huge openings,

and the apartments above can be offset with crazy overhangs.

Nehemiah: A vierendeel truss is actually a brilliant solution

for a long cantilever.

They were developed by Arthur vierendeel,

a 19th-century Belgian engineer

who developed this super strong truss

particularly resistant to bending forces.

Hezi: The advantage of utilizing a vierendeel truss

is that it's not obstructive architecturally.

A traditional truss

would have a diagonal member crossing through the space,

and that would be very obstructive architecturally

and kind of prohibitive,

so we came with a different approach.

Narrator: So this is how the vierendeel truss

became the key to building the sky villas.

On super stable floor 47,

concrete columns are precisely placed

where they will give support to the floor above.

This creates the first vierendeel truss.

The central lift shaft provides all the lateral strength

so the floor remains beautifully open plan,

but can still support the tremendous downward forces

from the eight unique stories built on top.

These trusses create such rigidity

that the upper floors

don't have to sit directly on top of one another,

allowing the amazing overhangs,

all helping to make the sky villas

some of the most spectacular homes in the world.

Hezi: There's literally nothing underneath us

other than the slab.

And then it's straight down to the street level,

800 feet below us.

Narrator: Not only are they over 650 feet up,

at up to 5,900 square feet,

the nine sky villas are huge,

each exclusively occupying its own floor,

and each with a unique layout.

Situated in up-and-coming midtown Manhattan,

it was hoped homes here would fetch sky-high prices.

Hayley loren oakes: This is a building

@aimed at some of the wealthiest people in New York.

Narrator: The lower apartments up to the 45th floor

would be priced between $3 million and $10 million,

while the plan was the sky villas would sell

for over $20 million.

And those hefty price tags were needed,

as it became clear the top nine floors,

with their unique layouts,

were going to be slow and expensive to build.

Izak: You know, you do three, four floors

of all the same thing,

and then you're used to it, then it's just automatic.

Narrator: But of course herzog's nine sky villas

were all unique.

Hayley: Every floor plate is a different size and shape.

Izak: So every floor, there was a learning curve,

and then you learn that, and now it's a new plan.

It's just like, you know,

the game changed every time we poured.

Narrator: Because each of the sky villas is different,

before work could start on the apartment above,

the one below needed to be strong enough to support it.

And that meant more time for the concrete to set.

Hezi: The biggest challenge for the contractor

is to hold the forms and scaffoldings in place

until the concrete cures and reach its required strength,

and then he can remove the scaffolding

and the temporary supports.

Izak: You know, in New York,

we're used to pouring one floor every other day,

here some floors took six weeks.

Narrator: By 2014,

the lower 46 floors had taken 20 months to complete.

And with the top nine floors set to take nine more months,

extra measures were taken

to make the site safe and weatherproof.

Hezi: It was actually very interesting

to see during construction

that it had this black curtain protection

around the entire 10 floors.

Once everything cured,

they start stripping down the scaffolding,

and then this beautiful structure,

it's almost like a sculpture,

revealed itself to the public.

Narrator: So with Patience and engineering ingenuity,

the impossible overhanging sky villas had been created.

But before anyone moved in,

the building needed protection

from something that spells trouble

for any skyscraper...

The wind.

Joshua: Tall buildings will always move in the wind,

and that can't ever be completely stopped,

and they'll always move...

In some cases, by quite a lot.

Narrator: New York has recorded winds

of up to 100 miles per hour,

and Leonard street's sheer height

and comparative isolation from other scrapers

means in high winds it can move by up to a foot at the top.

It's engineered to handle this amount of movement,

but left unchecked,

these movements can keep on increasing,

potentially collapsing the building.

So it's crucial there's something

to counteract these forces.

Corina kwami: A lot of skyscrapers

have what's called mass dampers.

They're basically counterweights.

So, for example, if the wind is pushing one way,

the counterweight pushes the other way.

Narrator: Most skyscraper counterweights

are large suspended blocks like this.

But at Leonard street,

they chose a damper system sometimes used to cope

with the ultimate threat to buildings...

Earthquakes.

Skyscrapers in earthquake zones have water tanks

to cope with the swaying induced by a massive quake.

This is what 56 Leonard street uses.

Hayley: At the top is a giant a tank of water.

When the building moves one way due to the wind,

the water in the tank moves in the opposite direction.

Narrator: So 56 Leonard street

was ready for the forces of nature.

But in 2016, just a year from opening,

the engineers needed to get the inside prepared

for new residents.

To do this, a twist was given to an otherwise ordinary feature...

The lobby staircase.

Herzog: You have a stair,

so do the stair in the way that it's nice to walk up and down.

It's inviting, I would say, to take the stairs

if it's one, two, three floors perhaps.

Narrator: As usual at 56 Leonard,

the stairs would be made of poured concrete.

Debbie sterling: So the way to design something in concrete,

it's called form work,

and it's really simple.

It's basically just creating a mold

of whatever shape you want

and pouring the concrete in, letting it dry,

and there you have it.

Narrator: Sounds simple,

except when the pour involves nearly 50 tons of concrete

and the architect is demanding a seamless finish

for his stairs.

A seamless finish is created

by not letting the concrete set between pours,

so preparations needed to be meticulous.

Hayley: It took five months to plan the stairs

and create the mold

that the concrete would be poured into.

Izak: It started with experts conducting the whole pouring

because concrete has air bubbles in it,

and that's why they use vibrators.

This guy was conducting everybody

where to use the vibrator.

It was a very, very precise operation and a long day.

Narrator: The carefully poured staircase

was typical of the attention lavished

on every inch of this building.

Once finished in 2017,

the quality of Leonard street was obvious.

But potential buyers

had understood this was a special building

way before that.

Sales had opened in 2013,

and almost immediately

someone agreed to pay $47 million for a sky villa...

A record for any address below midtown Manhattan,

and a sign that the risks taken by its developer,

izak senbahar,

would pay off.

Izak: I think we broke a record.

We sold close to a billion dollars

in nine months.

Narrator: 2.5 million man hours,

nearly 100,000 cubic feet of concrete,

and 5,000 tons of steel

went into creating Leonard street's

half a million square feet of space.

It had taken over five years,

but a towering landmark now graced Manhattan's skyline.

And if proof of its success was needed,

locals have affectionately given 56 a nickname.

Jacques: Someone spoke of the jenga tower.

At the beginning, I didn't even know what he was talking about,

but, um, people like it, and, um...

If people like it over a certain time,

this is a good, good sign.

Izak: It was difficult.

It was 10 years of my life.

But to build a building like that in the skyline,

it always feels good

that, you know, you've built something like that

corina: 56 Leonard is remarkable.

I mean, it stretches the limit of what's possible to build,

what's structurally possible,

and then celebrates that.

Narrator: 12,000 miles from the ma

of Manhattan

are mother nature's skyscrapers.

The towering sandstone columns and miniature rainforests

of zhangjiajie national park in central China

are a unique spectacle on planet earth.

Corina: This is a unesco world heritage site.

Beautiful yet strange landscape.

There's nowhere else like it.

Narrator: Unsurprisingly,

millions of people want to see it,

and what's the best way to enjoy that incredible view?

By taking the world's tallest outdoor elevator.

The 1,000-foot-high elevator of a hundred dragons

is better known as the bailong elevator.

Joshua: This is the elevator

that hangs off the side of a cliff.

It's taller than the Eiffel Tower,

taller than the shard in London.

Narrator: The site was so remote

that heavy machines couldn't be used to build it.

All the work had to be done by hand.

Hayley: It carries 1,380 passengers an hour

and all in the middle of an earthquake zone.

Narrator: But laser systems and escape tunnels

keep the tourists safe from the seismic danger.

Debbie: And if you don't want to take the elevator,

you can just go ahead and take the 999 stone steps.

Narrator: Stepping all over the park

is exactly what thousands of people used to do.

In the 1990s,

word about the stunning landscape spread,

and soon, huge numbers of curious tourists

were tramping through the delicate forests

and climbing its fragile rocks.

Its ecosystem was suffering.

The Chinese government had to act.

One of the best views of the park is from this peak.

So to keep visitors under control

but still let them see the incredible natural wonder,

they built this astonishing elevator,

half inside, half outside a huge rock face.

The visible 550 feet

is actually only just over half the elevator's total height.

The lower 500 feet

is hidden in shafts tunnelled inside the cliff.

And at the bottom of those is a 650-foot access tunnel

leading to the main concourse.

It all works smoothly now,

but its creation was an epic feat

of human endeavour and engineering.

The first stage was to tunnel into the mountain

to where they were going to build

the base of the lift shafts.

Today, it's used by hordes of visitors

to reach the elevators

after they've gotten off their coaches.

But when the project was started in 1999,

road access was severely limited

and no heavy equipment could be brought in.

Liu jie is manager of the elevator facility.

[Speaking Chinese]

Liu jie, translated: We used 100% human labor,

with no heavy equipment and industrial machines

used during construction.

Workers carried all the equipment and materials

on their shoulders or with their hands

to the hillside.

Narrator: So using only hand tools,

the tunnellers got to work.

Jie, translated: We first dug a tunnel

into the mountain at its foot.

Then we drilled the elevator shaft in reverse,

from bottom to top.

Narrator: Yes, you heard correctly.

They drilled the shaft upwards.

This is called reverse circulation drilling.

Jie, translated: Drilling Wells from bottom to top

is actually very difficult and dangerous,

as the Wells above the workers can collapse at any time,

and yet workers had to keep drilling upward.

Narrator: With the 500-foot shaft reinforced,

the exposed mountainside above

needed to be made much more stable and strong

before it could take the weight of the elevators.

Jie, translated: More than 4,000 rock bolts

were inserted up all 326 meters of the mountainside,

and anchor cables were connected to the rock bolts

so they could surround the mountain.

Narrator: With the 500-foot shaft reinforced,

the exposed mountainside above

needed to be made much more stable and strong

before it could take the weight of the elevators.

Next, the huge steel derricks, or frames,

were bolted on the reinforced cliff face.

Finally, the elevator cabs would be installed.

Those three huge double-Decker cabs

can each carry a payload of almost 5 tons,

or over 50 people.

With their high speed of over 16 feet per second

and world-record 1,070-foot climb height,

they demand state-of-the-art control systems.

Computers kept the cabs balanced and smooth in transit.

To save power,

electrical energy is recovered by the motors

as the cabs descend.

But perhaps the most important engineering at bailong

are its safety systems,

because the stunning beauty of the zhangjiajie region

hides a deadly threat.

Joshua: It is an earthquake zone

where they've had historically quite significant earthquakes

that have killed a large number of people

in the vicinity and in the surroundings,

and it's something that could happen again.

Narrator: With the elevators in almost constant use,

raising over 20,000 people up to the viewing platform

every day of the week,

the consequences of a major quake

could be catastrophic.

So bailong's engineers

have built in every safety feature they could

to quake-proof the structure.

Jie, translated: We have seven wire ropes

above the cab,

and actually, every single one of them

can hold the weight of the cab.

The second safety measure

are the guide rails along both sides of the cab.

The cab is tightly fitted to these rails

and has brakes which will stop the elevator from falling

even if all seven cables fail.

The third safety guard

are the four hydraulic bumper posts

we installed in the elevator pit.

This is to soften the impact of the cab

if the other safety gear fails to work.

Narrator: Of course, prior warning of an earthquake

would be the best safety feature of them all.

Just a few seconds' warning

could save hundreds of lives here.

So a system of lasers is sighted on distant hillsides,

which train back to receptors

mounted onto the steel structure.

Hayley: The lasers shining across the mountain

are extremely sensitive.

They can monitor the tiniest of movements in the earth

and can notify the control room

to perform evacuation procedures.

Narrator: Just a few millimetres of movement

will trigger the alarm,

and instantly,

the elevators will automatically take passengers

to one of the evacuation exits,

built every 36 feet into the cliff face.

For now, the earth moves only for those lucky enough

to gaze at one of the planet's great natural wonders.

Jie, translated: Since 2015,

we have experienced an explosive increase

in the number of visitors,

with about 4.5 million tourists coming here in 2018.

Narrator: The park is now

the second most popular tourist attraction in China,

and it's being kept in pristine condition,

all thanks to the engineers

who figured out how to build this incredible elevator.

Paris, France.

Carefully planned.

Very traditional.

Famous for its immaculate boulevards

and ornate apartment buildings,

all combining to create its unique character.

No wonder, when bold new structures are proposed,

it often takes a while before the parisians appreciate them.

In 1889, the Eiffel Tower was described

as "a truly tragic street lamp;"

in 1977, the Pompidou centre simply "monstrous."

And in 2006, a new building joined their ranks.

Debbie: This building is definitely out there.

It's weird.

You look at it, and you're like,

is it a broken perfume bottle?

Is it a giant ship?

Is it a ufo from outer space?

Narrator: A building designed

by one of the world's greatest architects

that locals hated

and set out to stop.

Man: In Paris,

it's difficult to imagine this kind of a building.

Narrator: Bankrolled by a billionaire,

money was not the problem.

Figuring out how to build it was.

Man: I think it's fair to say there were some very dark days

in the process of putting this building together.

Narrator: The challenge of creating

this astonishing building

took hundreds of engineers, architects, and craftspeople

eight years and 800 million Euros

to overcome.

So, how did they do it?

When a man worth $100 billion

decides he wants a new building for his art collection,

he doesn't just buy one at random.

Instead, in 2006,

luxury brand magnate Bernard arnault

got in touch with the man described

as perhaps the world's most important architect.

94-year-old frank gehry

dreamed up Bilbao's guggenheim museum

and the extraordinary Lou ruvo centre in Las Vegas.

This time, gehry was inspired

by the great glass palaces of the 19th century

and designed a building that would set a new benchmark

in extreme engineering challenges.

The 126,000-square-foot building was to be called

the Louis Vuitton foundation museum.

It would include a massive waterfall,

11 galleries,

and a 350-seat auditorium.

It would have huge steel icebergs

and all be shrouded in 12 billowing glass sails.

The budget was a cool 130 million Euros.

Frank gehry's buildings were already notorious

for challenging engineers' abilities to innovate.

This building would take that reputation to the next level.

James cowey spent a decade of his life working it out.

James cowey: This was not a smooth ride down the river,

as we say.

Myself and the engineers went to Los Angeles

to meet with gehry partners

as they proudly showed us their model of the building,

what they intended to build.

And they did a very, very long exposition,

and they finished by saying, "well, what do you think?"

And the structural engineer next to me thought for a second

and then said, "I think you used a lot of glue

to make your models stand together."

Narrator: Gehry's "glue happy" model makers

had good reason not to confront the question

of how to build it.

The design's sheer originality

meant there was no structural template to follow,

nothing to suggest it was actually possible.

But cowey's team took a logical approach

to planning the build.

James: It's a very tricky and complex building

geometrically, obviously,

when you see it from the outside.

You could break it down to four basic systems

that put the building together.

Narrator: The engineers devised a solution

that was based on illusion.

The huge glass sails appear to be supported

by the small curving structures known as the icebergs.

A signature of frank gehry designs,

they look like the core of the building,

but they're not.

Melt away the icebergs,

and some very conventional concrete cubes emerge,

within which are the gallery spaces themselves.

Now, these are not very gehry,

but they are very solid

and allow the building's outer skin of sails

to be so extreme.

Nehemiah: They give the appearance

as if the sails are floating in the air unsupported,

but obviously we know

that levitation of buildings hasn't been invented yet.

Narrator: To give the appearance of levitation,

the flimsy glass sails

would need many more smaller fixings

because, of course, being sails, strong wind was a big concern.

The forces of gravity and wind on a building

would normally be calculated by computer models.

But so much was unknown about these ultra-complex structures

that computer modelling wasn't trusted.

Getting the plan right meant going back to the basics.

James: We built a mini building,

which was not more than 50 square meters on the ground.

We have all of the systems...

The sails, the glass enclosure, the icebergs.

And we did a test run

in which we evacuated many of the problems

that we would have been confronted with

if we had built without doing this test.

Narrator: The successful dry run

of the Louis Vuitton foundation museum in Paris

gave the builders the green light.

By 2011, the project had been underway for over five years.

But as the foundations and central concrete structures

began to appear,

protests about the size of the building

and its impact on the park intensified.

Nehemiah: A group of Paris residents challenged it.

They didn't like it.

They challenged the original construction permit.

Narrator: A court order

found the building contravened parisian planning laws.

The huge project was stopped in its tracks.

James: When we were asked to suspend construction,

we were quite in the middle of things.

And so we had to keep working for another two or three months

just to stabilize the building so work could be suspended

because it was in a bit of a precarious state.

Narrator: With one-third of all the scaffolding in France

on site,

gehry, arnault,

and the hundreds of specialists involved

found their dream in the hands of the courts.

But Bernard arnault fought back.

The court battle ended four months later,

when the city of Paris suddenly changed its laws on land usage.

Frank gehry was back in business.

While the foundations and concrete cubes

were taking shape,

the components that would create

the steel icebergs and glass sails

were being made off site, a long way from Paris.

Gehry's mixed use of material was typical and challenging.

Arcing beams of wood and steel

support impossibly complex glass panels,

many exposed to the elements.

Making these to the highest standards

meant using only the very best workshops and craftspeople.

Engineer Bernard vaudeville

helped coordinate the massive Europe-wide project.

Bernard vaudeville: All the elements

are prefabricated,

they are made in workshops

which are 100 kilometres away from Paris.

For the glass, it's made in Italy,

and the wood was made in Germany,

and some other elements were made in Belgium,

so all these elements had to come from far away

and they were all prefabricated.

Narrator: More than 400 specialist fabricators

in four different countries

would create the 23,000 unique pieces

that must somehow all fit together perfectly

when assembled on site.

Ellie: That's basically the Jigsaw puzzle from hell.

Narrator: So how did they make sure

it would all slot together?

The designers used a system created for a very different

but even more demanding industry.

Hayley: The designers used a technology

pioneered by the aviation industry.

It's called b.I.M.,

building information model.

It lets all of the manufacturers add information to a 3-d model

and then lets the designers check what everyone is doing.

Narrator: This shared virtual building model

meant teams on site and off site

were all fully aware of any problems arising,

and could rapidly plan solutions,

dodging time-consuming meetings and expensive mistakes.

James: Basically this model was the base

on which everything was created.

And it allowed for the contractors

in different parts of the world to fabricate pieces

of amazing geometrical complexity.

Narrator: First of the prefabricated structures

to be assembled on site

were the icebergs.

Cedric joie: We're here in the iceberg,

the highest one.

These shells were prefabricated in Belgium

and were transported to the site, to Paris,

on trucks, trailers,

and assembled, as you can see, with bolts,

simply bolts,

with joints that you can see here.

All of these shells were different.

There were 365 different shells

for all the icebergs of the project.

It was assembled on site

to compose the external shell of the iceberg.

Narrator: Now the iceberg shells needed to be clad

with a huge number of custom-made white tiles,

which all had to be just the right size

before they arrived.

Corina: Normally it doesn't matter

if you have to adjust things on site.

I mean, that's part of the building process.

But you can't really do that if everything is so custom-made.

Narrator: Instead,

Bernard's team relied on components being made

to within a few millimetres of specification

so they weren't too close or too far apart,

once assembled.

Bernard: Assembling them on site is very difficult

because there is something we call tolerances.

Tolerances means that when you fabricate something,

it's never exact, never.

You can't do that. Exactitude is only divine.

It doesn't exist.

Narrator: Because every tile is different,

each one had to be attached in precisely the right order.

Cedric: You have 19,000 of these white panels.

Almost all are different.

Bernard: So they came in boxes.

When you opened the box,

the panels had to be in the right order.

You can't open 50 boxes

in order to find where the good panel is.

Narrator: The icebergs complete,

next came the huge sails.

With nearly 140,000 square feet of curving glass,

these were perhaps the most challenging features of all

to create.

James: 3,500 panels of glass,

with each one with an individual design

for which special ovens had to be created

to manage the curve,

to manage the way the surface would be treated

to reflect or not reflect light.

Narrator: Commercial car windshield-making

combined with meticulous hand craftsmanship

to ensure each panel curved precisely the right way

and was safe to install.

James: There were multiple, multiple constraints

just on the glass

that required us to work with glass manufacturers

to invent a whole new way of fabricating glass.

Narrator: Finally, in 2014,

eight years after it began

and with nearly 800 million Euros spent,

the Louis Vuitton foundation museum

was ready to hold its first exhibition.

But for many, the art inside was a sideshow,

because frank gehry,

his architects, engineers, and craftspeople

had achieved something extraordinary.

Joshua: The thing I really love about this building

is that the structure is on display.

So many buildings, the structure, the actual bits

that hold up the weight and the floors,

it's just not visible.

It's behind walls, it's behind cladding,

you never see it.

But with this structure,

@you can really see the columns, the frame, the skin.

And to me, that's really inspiring.

Corina: Beautiful.

But the work that went into it was extraordinary.

Narrator: Against what seemed impossible odds,

Paris had a new icon on its skyline

to match perhaps even that famous tower of steel.