Original subtitles

Narrator: What happens

when the world's most radical architect

tries to revive a hundred-year-old building?

Man: This project obviously stands and falls

with structure.

I mean, this is a structural masterpiece.

Narrator: How is one of the world's

tallest residential skyscrapers

even standing?

Man: Columns are what make a building stand up.

You take away that structural support

and...[imitates explosion]

Narrator: And how do you create a building

that would have been impossible just 10 years ago?

Woman: Building in water

is incredibly difficult.

You've gotta hold back an entire river

while you're building.

Narrator: This is the age of the extraordinary...

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

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 are revealed.

Discover the incredible stories of their construction...

Woman: These are extraordinary feats of engineering.

Narrator: To try and understand

how did they build that?

Ever-growing cities are in a constant battle for space,

risking demolishing the old to make way for the new.

But in antwerp, Belgium, one of Europe's busiest ports,

a forgotten 100-year-old building

has been transformed beyond imagination.

A ground-breaking architect has turned this historic firehouse

into a landing pad for an extension

that is truly out of this world,

challenging engineers to float the new addition effortlessly

above the original building...

Hayley loren oakes: It leans forwards, it's backwards,

it's completely off centre on the legs.

Narrator: Manufacturing the entire structure off-site,

and then shipping it in massive 400-ton pieces.

Ellie cosgrave: We're dealing with making sure

we protect this precious building

that lies underneath.

Narrator: Breathing new life into every inch of its new home.

This is the antwerp port house.

So, how did they build it?

The antwerp port authority,

the government body that controls the busy port,

needed a new home.

They decided on a long-forgotten firehouse

in the centre of the industrial complex.

It needed some serious work

if it was going to function as their new headquarters,

but they didn't want to demolish the original listed building.

Joshua macabuag: Adding to existing historical structures

is a real challenge.

You've got the technical challenge

of being able to work around and load and repair

what can be quite old and historic material

of the building.

But then you've also got the aesthetic

and the kind of heritage issues as well.

You need to build something

that's gonna be true to the original history

and aesthetic of the structure

or complement it in quite a stark and interesting way.

Narrator: They brought in

one of the world's most famous architects,

zaha hadid,

to come up with a solution.

Her visionary designs, like the Guangzhou opera house,

were known for pushing engineering to the limits.

It needed some serious work

if it was going to function as their new headquarters.

But they didn't want to demolish the original building.

Joris pauwels: This is maybe the biggest and most prominent

existing building we've taken on

to develop into a new overall project,

@and it's definitely a challenge,

but it's something that we relish,

it gives all kinds of new perspectives

on how to deal with existing fabric, urban fabric.

Narrator: They had to figure out

how to build a futuristic extension

to create a space to house new offices,

while protecting a beautiful historic building

that would form the rest of the port authority's

new headquarters.

Joris: The original design

had four equal facçades,

meaning there's no front entrance.

The four sides were equally important,

so we definitely wanted to preserve

that quality of the existing building

by building a volume on top

and not blocking visually one of the main facçades.

Narrator: The architects also wanted

to preserve the building's central courtyard.

Conservation specialist Philippe lemineur

was charged with protecting this piece of antwerp's past,

making sure the radical design didn't destroy the building

or Rob it of its original identity.

Philippe lemineur: We can see in the typology

of a fire station a lot of elements.

One you can see on the right side

is that there are a lot of gates for fire trucks,

and then you have the back side in the middle of the facçade,

the dry tower.

Those elements are very important for a fire station.

Narrator: Studying the plans for the firehouse

gave the architects an idea...

One that would honour the original design

and let them build something out of this world.

It turns out the building was never actually finished.

Joris: It was built in 1921,

and the original design of the fire station

had a big tower on top,

which was twice the size of the building,

very extravagant, was never built,

and which made us consider

an extension on top of the existing building

as a kind of contemporary endpoint

to the existing building.

Narrator: This monumental extension

not only brings the building into the 21st century;

it completes the vision of the original architect.

The plan was to build

a precision-engineered futuristic extension

over 60 feet above the historic building

to house new offices,

supporting the 1,500-ton structure

with two massive concrete legs,

and to join the new extension to the firehouse

through the old tower,

where the firemen used to hang their hoses to dry.

The engineers got to work

figuring out how to support the massive steel structure

above the 100-year-old building,

without damaging it.

Joris: This project obviously stands and falls with structure.

I mean, this is a structural masterpiece.

We'd like our buildings to float if we can,

so we definitely try to minimize the points

and keep this idea of a hovering,

large hovering volume over the existing building.

The new building cantilevers out

over the square in front of the existing building.

It's quite a dramatic effect,

pointing towards the city centre of antwerp.

The structure of the new building

is a steel structure.

It's held by two concrete pillars.

Narrator: The engineers built two concrete legs

to hold up the new offices,

with the front leg designed to widely lean out.

It looked dramatic,

but without precise calculations,

it risked dropping the brand-new building

on top of the firehouse.

Ellie: Because the front leg is leaning out at an angle,

it's gonna want to push out at the top

and slip under the building at the bottom.

Narrator: They decided to connect the front and back legs

at the top and bottom,

turning the structure into a massive concrete ring,

with the bottom part of that ring underground.

Corina kwami: By connecting these two legs at the top,

they are kept from falling out at the top,

and at the bottom, stopped from slipping in.

Joris: The two pillars are obviously not vertical,

so that we have a very dramatically inclined

front pillar,

which needs the concrete ring

to keep it from falling over the square,

so that's why this ring is very important

as a structural element.

Narrator: The ring is joined

just under the massive steel and glass structure,

and the bottom connects these stories

underground in the carpark,

keeping the legs in place

and letting them support the weight of the extension.

The top section stops the giant concrete leg from falling over,

and the bottom stops it sliding out

from under the massive steel structure.

The whole thing is steadied by another four

internal-connected steel supports.

The engineers did all this

while barely touching the old firehouse.

Joris: We tried to keep the impact

on the existing building very minimal,

and that is equally important

when we created this structural ring,

which goes through the foundation work

of the existing building,

so it's a very minimal connection,

both structurally, where we connect the foundations,

as well as physically

where we introduced the small staircase

leading up to the entrance hall inside the existing building.

We've got a two-story underground car parking,

so it's two stories down.

Underneath that,

so the third basement level, if you like,

that's where we made the connection

between the foundation of that inclined front pillar

and the central pillar, which rests in the courtyard.

Narrator: What did the conservation specialist think

of this radical approach?

Did it do justice to the original building?

Philippe: The opportunity to do the second feet

at the inside of the building, in the courtyard.

But we still needed to have the aspect of a courtyard.

You can't fill it up with feets and structure.

Then you have no more courtyard,

and you have no more light inside.

You can use even more this space.

So the engineer and zaha hadid tried to find a way

that you could have this structure,

but with the kind of subtlety

that these are sculptural elements in the inside,

and so, you can see that those elements,

even not touch the old structure...

Just landing inside the building,

and they make possible that this big volume above our heads

is standing over there.

Narrator: With the gigantic concrete legs in place,

the engineers were ready to tackle

the futuristic glass structure.

But constructing it was going to be a bigger undertaking

than anyone had imagined.

Joris: Having the new building floating in mid-air,

it's important that it's not a super heavy construction.

So it's a steel structure.

It also is a sustainable structure.

So we looked at the whole number of possibilities

of constructing the building.

We did a lot of analysis with the contractor

to see how they could build platforms,

how they could get enough people up there.

Narrator: To preserve the original building

and realize the precise design,

the engineers decided to build almost all of the new extension

in a factory 55 miles away.

Joris: It was clear, after initial analysis,

that building the steel structure off-site

in big modules,

shipping them to site, and installing them

was a much faster and more economical way

of constructing the building.

Corina: Normally with steel structures,

you build upwards with scaffolding support

and welding as you go.

But in this case,

they were building over the existing structure.

You're looking at a lot of scaffolding support,

with all the risks of building over and around

this listed precious building.

So what do you do?

You build it 90 kilometres away, in 400-ton pieces,

and ship it in.

Joris: So building the structure of the new building

off-site in factory

means it's much more controlled in terms of tolerances,

making sure everything is completely right.

They even installed a temporary structure

to ship the modules on boats to the location,

and then all they had to do is lift them in place,

so it's a much faster construction procedure

to build the overall volume.

The structure of the new building

is built in six separate steel parts,

two steel pieces per level,

and they were lifted in place

and then assembled on top of the existing building.

Narrator: The 330-foot-long, 200-foot-high,

and 65-foot-wide steel structure

was broken up into six enormous 400-ton pieces

and shipped from the factory 55 miles away on massive barges.

The builders used a remote-controlled Dolly system

to offload these giant sections.

Joris: So it's both light construction,

it's lightweight construction time,

which is important,

and also the kind of environmental concern

that we had,

so this is achieved

by having this steel structure made off-site

and coming on site by boat.

Hayley: The scale of this job is immense.

Just look at the size of the platforms

that are used to drive off the sections from the barges.

They're each the size of a truck.

It just seems mad that this is the safest and quickest

and most efficient way of working.

But it just illustrates that to make a building like this,

you really have to approach it

from a completely different way of thinking.

Narrator: With the steel mega structure in place,

they turned their attention

to the building's signature glass facçade.

Joris: We wanted a glass volume to maximize views out,

maximum light coming into the office environment.

And what we looked at

is to create a dynamic over the length of the facçade,

as if this building is in motion.

And we did that by playing with the faceted triangles

that go from a flat facçade on the south side

to a completely faceted pineapple structure

on the north side.

So this transition makes that,

when you observe the building from distance,

it seems to be in constant flux with light, with clouds,

with sunlight playing on the triangles.

It seems to be a kind of moving object

over this static classical building.

Corina: The finished effect

means the glass is constantly changing

as you walk around it.

There's something of the effect of the glittering sea

or fishy scales.

Narrator: The gigantic extension was secure,

glistening above the old firehouse.

But there was still no physical connection

between the two structures.

How do you connect two massive buildings

with the least impact possible?

They decided to use the firehouse's old dry tower.

Philippe: You do an extension to a building...

At one place or at one moment,

the two parts have a place where they meet together.

What we see is

maybe the only physical touch between old and new

is the dry tower.

When we see the dry tower,

we see a little bit of masonry above the roof,

and then we see the start of a glazen elevator shaft.

The elevator starts in the old dry tower,

go to the glazen shaft,

and then enter in the new building.

Joris: Although you enter the lifts

at the bottom of the existing building in the tower,

the lifts take you up to the new building and connect,

but the structure of these lifts is hung independently

from the steel structure of the new building,

so there is, it's not actually touching the brickwork

of the existing tower.

The existing brickwork tower acts as a sleeve

in which the steel structure is hung

independently from the brickwork,

completely loose from each other.

Corina: The amazing thing

is that both of these buildings are separate.

Replace the bricks, and good as new.

Of course, that would be a very expensive change of heart.

Narrator: The radical new extension was in place,

transforming the original fire station,

seamlessly combining groundbreaking architecture

with a sense of history

to bring a forgotten firehouse into the 21st century.

Joris: I think actually that our project

allowed this building to be reinstated

as an important landmark within the antwerp urban fabric.

There might have been all kinds of other scenarios

where this building would have been demolished

and something new would have been built.

I think it was very important also for zaha herself

to keep this existing building, to stay with this,

and to have a separate layer coming over it

to layer the city,

instead of demolishing and rebuilding.

Philippe: We have a larger building

with a bigger capacity,

working 500 people in it now.

And we have also a remarkable site now here,

a site maybe forgotten in the past.

Ellie: What we have here is a building

that deeply respects the original

and gives it space.

Yet it also reacts against it,

with something so crazy and outlandish.

The overall effect is that we have these two structures

that exist together

but have their own identity.

Narrator: Deep in the heart of New York's Manhattan island,

one of the most prestigious addresses in the city

has a new resident.

An 88-story skyscraper,

one of the highest residential towers in the world.

It's classed as a "super tall."

Corina: There's only about 146 of them in the world.

Nehemiah mabry: It's really become a club

that people are desperate to be a part of.

Narrator: Not just tall in the extreme,

but at just 92 feet across,

it's also very slim

and vulnerable to the city's wild winds.

Debbie sterling: 432 park Avenue

is 15 times higher than the width of its base.

Narrator: To create luxury apartments

with unspoiled views,

the engineers had to do away with internal columns.

The project would cost $1.25 billion

and push skyscraper engineering to its limits.

This gravity-defying wonder is 432 park Avenue.

It's 2011,

and on a small plot in Manhattan,

an ambitious plan is being put into action

to build a 92-foot-wide tower

and just under 1,400 feet in the sky...

Dimensions never seen before in skyscraper engineering.

Engineer hezi mena was tasked with figuring out

how to build this developer's dream.

Hezi mena: It's not a normal typical building.

It's very tall, small footprint, it's very slender.

There was a lot of challenges.

It's a tremendous effort put in for over five years

from start to finish.

Narrator: This super-tall, super-slim design

was difficult enough to build as it was,

but there was another curveball coming the engineer's way.

With the apartments needing to fetch $75 million plus,

no one wanted internal columns

getting in the way of luxury interiors.

They told the engineers to get rid of them.

Joshua: Taking away columns is all well and good,

but unfortunately they're very important

for holding up the structure.

If you take them away, úthen you need an alternative way

to carry those loads down to the ground.

Nehemiah: Columns are what make a building stand up.

You take away that structural support,

and...[imitates explosion]

Narrator: With a building this tall,

you need a way to hold up the weight of 88 floors.

Normally this is done with internal columns.

Without them,

they needed a way to support this super-tall skyscraper.

Hezi: So like a typical 20, 30-story building

would have a central core,

what we call the backbone of the building.

And that will hold wind and the earthquakes,

seismic, horizontal forces.

Ellie: This is the backbone of the building.

It's what gives buildings their strength.

Narrator: For 432 park Avenue,

at 88 stories high,

that wasn't enough.

The engineers decided

to make the building's outer shell super-strong

to reinforce the structure.

Hezi: This building has a backbone,

which is also the central core.

But we also supplemented the exterior columns,

so together they are providing the stability

that the building needs.

Narrator: They inserted supersized steel rebar

into the concrete outer shell

for added strength.

Corina: To make concrete stronger,

you put steel reinforcement into it.

Ellie: And in this case, it's a gigantic piece of steel.

Narrator: Architects Chuck knapp and Gloria glass

kept a section of this super thick rebar

as a souvenir.

Chuck knapp: You can see the size and the diameter.

These are major rebar, and...

Gloria glass: In general,

they are this size, you know, right?

Chuck: The information'súon the side of the bar normally.

Not this, this is screw,

because they need to be able to screw these in the couplers,

so it's a different animal.

Um, but it's pretty big.

And this thing's only about an inch, inch and a half,

and it's very, very heavy.

Narrator: It wasn't enough, though,

just to have a super strong facçade.

Corina: It had to be tied to the core of the building,

that area that houses the elevator shaft.

Narrator: This supersized rebar

made the outside of the skyscraper

incredibly strong,

but the engineers made it even stronger,

connecting it with steel beams to the concrete elevator shaft,

which acts like a spine

running down the length of the building.

The skyscraper's core and reinforced exterior

gave it the strength to tower almost 1,400 feet into the air.

But this height made it vulnerable

to New York's infamous winds.

Hayley: A skyscraper is a structure

that people live in.

You hang out there, you sleep there.

And if the architects and engineers

don't do anything about the wind,

then you're really going to feel it,

especially if the building's thin.

Ellie: All structures that we build move,

but in tall structures,

they're particularly prone to being moved by the wind,

and the thinner the structure, the more vulnerable they are.

Narrator: The skyscraper was vulnerable

to turbulence created by the wind.

If the wind was strong enough,

it could make the building shake,

making it uninhabitable

and even risking damage to the structure.

Joshua: When you have a tall, thin structure like this

and when the wind strikes it,

the wind then wants to pass around the building,

creating turbulence on the back side.

That turbulence creates vortices and swirls of wind

which pass up the full height of the building,

and the turbulence creates the swirls

to first be on one side,

and then the other, and then the other.

This is called vortex shedding, and what it does

is it starts to actually to buffet the building sideways

even though you're blowing it straight on.

Now, any building has a natural frequency.

Think about pushing a child on a swing.

If you push the child at the right frequency,

the child will start to go higher.

Same thing happens to a building.

If these vortices start to form

and push the building at the right or the wrong frequency,

then the vibrations will start to get out of control.

Narrator: The engineers started to take out windows,

letting the wind rush through floors

that contain the skyscraper's pumps and other utilities.

Hezi: We found that when you make these penetrations

in the building at certain locations,

it reduces the wind pressures by about 20% to 25%.

Hayley: Every twelfth floor is open to the air.

That lets the wind blow through.

Really clever.

But it doesn't solve the problem completely.

Narrator: To make sure the skyscraper

could survive even New York's strongest winds,

the engineers had another trick up their sleeves.

The masterstroke, the brilliant engineering trick,

is hidden away at the very top of the tower,

on the 84th floor...

Two secret giant machines that directly counteract the wind.

Joshua: The wind acting on the building

wants to make it sway.

To stop that happening, they've used tuned mass dampers,

which means a huge lump of concrete

high up in the building.

It's an active system,

which means that when the building

wants to sway in one direction,

the hydraulic Jacks

will move that lump of concrete in the other direction,

counteracting that force

and hopefully keeping the building

not moving too much.

Hezi: This particular building,

we have a damper, weighs about 1,300 tons,

absorbing the energy of the wind that exerts on the building.

So it has to be fast enough

so the occupant that sits in the apartment

doesn't feel the movement of the building.

Narrator: Which is good news

if you've paid over $75 million

for one of the incredible apartments.

Ellie: 432 is without a doubt

a feat of world-class engineering.

It costs a staggering $1.25 billion to build,

and by my estimation,

it's about as beautiful as a skyscraper can get.

Narrator: 432 park Avenue towers above the competition,

giving it one of the most sought-after addresses

in New York.

Its best view as well,

using clever engineering

to take skyscrapers to their limits.

On the rugged east coast of Scotland,

a ship-building powerhouse had fallen quiet.

But all of that was about to change,

thanks to one extraordinary structure...

The brainchild

of one of the world's most radical architects.

The Victoria & Albert museum in dundee

rises from the river tay,

forming a man-made cliff.

This revolutionary design

forced engineers to construct a huge dam

in the middle of a raging river...

Build a gravity-defying 86,000-square-foot shell

in one piece of concrete,

without a column in sight...

And hang 3-ton slabs off impossible walls.

Ellie: It looks like the forces of this building

should just completely rip it apart.

Narrator: So, how did they build it?

In dundee, Scotland,

the city's industrial heart needed a kickstart.

The radical plan was to build Scotland's first design museum

in the historic shipyards,

where Scott's and shackleton's legendary antarctic ship

had been built.

Phillip long: It's been very important in this project

to have a remarkable building.

This is a new design museum,

so it seemed right to look for an ambitious design

that would inspire people to come and see the building,

a building by an architect who is so brilliant

at responding to a particular place,

about the relationship between the river and the city.

Narrator: Visionary Japanese architect kengo kuma

designed this brutalist masterpiece.

He used Scotland's stunning landscape

for inspiration.

Narrator: The plan...

To lay the foundations in the middle of the tay river,

while battling the Scottish weather

and protecting local wildlife...

To cast a giant concrete shell

that uses nothing but its own strangely shaped walls

for support...

And hang the signature cladding,

with pieces weighing up to 3 tons

from the gravity-defying walls.

Their first task was to lay the foundations,

but this wasn't going to be easy.

The design called for a huge portion of the building

to stick out into the tay.

@corina: There are serious issues with building in water.

Debbie: Building in water is incredibly difficult.

You've got to hold back an entire river

while you're building.

Narrator: How do you lay foundations

in the middle of a river?

Structural engineer Dan clipson

had to tackle this monumental task.

Dan clipson: Building in the water

isn't fundamentally different from building on the ground.

@the foundations of the building

still need to go down to bedrock.

So whether it's in the river

or on the land behind the river wall,

we're still piling down 20 meters into the rock

to get a good foundation for the building.

Dundee is a very nice sunny city most of the time.

It's also cold and wet in winter, like many places.

So the weather plays quite a key part in construction.

We're working by a tidal river,

working in a climate that has extreme colds during the winter

and rain and wind.

They all need to be considered during construction.

Narrator: They had to lay the foundations

on a seriously difficult site.

To make it possible,

they decided to build a dam

out of 12,500 tons of stone and earth,

called a cofferdam.

Corina: A cofferdam is an enclosure

built within a body of water

to allow the enclosed area to be pumped out.

Ellie: That means that you can get on with your work

in a nice dry environment.

Narrator: The cofferdam would let the engineers

extend the existing dockside,

pushing the site into the tay.

Building the dam was a race against time.

Phillip: There are protected species in the river,

particularly a species of seal,

and so we had a very short time-scale

that would allow us to build our foundation out in the river.

We went on site in march in 2015,

and we had to make sure

that all of that work that was done out in the river

was done by the beginning of June,

the beginning of the seal pupping season.

Narrator: The local grey seal population

lives close to the site.

Their breeding season was just around the corner,

and the second it started,

all work in the river would have to stop.

The construction team

hammered massive steel slats into the riverbed,

filling in the centre with rubble

to hold back the force of the tay river.

Dan: What was done in this case

was a temporary bit of land was created,

so the contractor installed a piled wall out into the river

and filled it in with ground

to create a new bit of land

that we could then build the building on.

We were constructing the building

on top of solid ground,

even though it was above the river.

Narrator: The engineers drilled down 65 feet,

anchoring the building's foundations

to the rock bed on concrete piles.

At the same time,

they would have to make sure the corrosive salt of the tay

wouldn't eat away the foundations.

They decided to use a concrete with a special formula,

specifically designed to resist salt.

Dan: Salt and chlorides are the enemy of our structure.

So they cause corrosion

and damage to the building over time

that we have to prevent.

The concrete mixes we've used in this building

had to be different.

We had to change them from what we'd normally do

in order to make them more resistant

to the elements, to the salts,

to all of the things that are trying to attack the building.

Narrator: The foundations were secure,

and a new piece of land had been built into the tay river,

ready for the next step of the build.

The engineers now had to tackle the building's radical shape.

They wanted the walls to support the entire structure,

removing any interior columns from the gallery spaces.

But the leaning and twisting design

threatened to tear the museum apart.

Hayley: Normally you would never build walls

that are sloping outwards,

and that's because,

as well as the usual gravitational forces

that are pushing down on the building,

you're adding an extra layer of strain

as the walls are being pulled apart.

Joshua: The shape of this building is,

it's really incredible

@and something that you don't see in architecture

very often for a reason,

@and that's because it just takes

a lot of expertise, science, and maths

to achieve what they've achieved here.

Narrator: To get the calculations right,

they used the very latest 3D computer modelling

and sculptural techniques.

Dan: This is a building that is a very modern design.

We needed to use a lot of computational power

to create the design of this building.

We looked at the shape at the concept stage,

and we could have put a frame in here

and hung the facçade off the outside of it.

It could have been a traditional building.

The problem with that is

we'd fill the building with a lot of stuff,

and this is a museum,

this is an art space, this is a gallery,

this is a place for people to come and enjoy

that we didn't want to fill with bits of steel and concrete.

Historically we'd build buildings

with the walls carrying the weight...

Stone huts back in the dark ages.

The walls carried the roof,

and that was how we protected you from the wind and the rain.

So we took the option of using the shell of the building

as its structure,

kind of going back to the old way of doing things...

Make the outside of the building hold the building up,

and then you don't need to put anything inside.

Because of the way the building is pulling

on all the different bits of itself...

The roof pulls on the walls, the walls pull on the roof...

We had to design it as one big object.

Narrator: To make the most of the exhibition spaces,

the architect didn't want any interior columns.

To achieve this, the shell of the building,

the exterior walls,

had to support the roof and themselves.

No easy task, given their extreme shapes.

The solution was to design the shell to work as one piece,

using its own weight and steel reinforcements

to hold the building together.

But there was a problem.

The shell would be only structurally sound

when the last piece was in place.

Until then, the whole building was unstable.

Joshua: So the leaning walls and the whole building

is really held together by these tension forces

pulling everything back towards that central core.

Dan: The skin of the building itself

is doing all the work.

It's carrying the weight of the building,

it's pushing and pulling with different forces,

it's resisting the wind and the rain,

it's keeping the building watertight,

holding the facçade up and the cladding on the outside.

But it's primarily supporting the building.

Narrator: They used their advanced computer model

to make the walls super-efficient,

making them as thin as possible, and more importantly, light.

Dan: That resulted in some of the walls

being half as thick.

They went from 600 millimetres down to 300 millimetres,

which is a significant saving in materials

and reduces the weight of the building,

the size of the foundations.

It's a lot of positive outcomes from that.

Narrator: Now they faced the challenge

of building the 81,000-cubic-foot shell.

This would only be stable

when the last pour of concrete had hardened.

It wouldn't be able to support its own weight

until the very end.

Dan: Because of the shell we had to make,

it was like casting a giant mold.

We had to finish the casting

before we could take the mold away,

'cause in a partially completed state,

the building isn't stable.

Narrator: As the shell started to go up,

the builders had to add more and more formwork...

The molds that hold the concrete...

To support the precarious structure.

If they removed a piece too early,

the whole structure would collapse.

After a year and a half of constant work,

the last concrete pour was completed.

It was time to take off the formwork

and see if all the calculations were correct

and if this one-of-a-kind design would support itself.

Phillip: Finally,

after nearly two years of it coming into place,

it came down,

and it was a very, very exciting moment

to see that formwork removed

and the shell of v&a dundee

finally born, finally revealed.

Narrator: When the molds were removed,

the black concrete underneath was revealed.

It was colourized with a pfa paint,

or pulverized fuel ash,

made from the waste of coal-fired power stations.

At last,

the v&a's groundbreaking shell was complete.

But architect kengo kuma wasn't going to leave it there.

He had big plans for the finish.

Narrator: He wanted to use giant concrete blocks

to mimic the craggy appearance of Scottish coastal cliffs.

But it turns out, creating a random natural pattern

is harder than you think.

Dan: If you look at the facçade of the building,

at the external panels from outside,

you'll see that they all look slightly different.

There's a random pattern to them.

They step in and out, they step up and down,

they kind of weave around

and create this sort of vision of this cliff face,

of this random assortment.

In reality, they're not that random.

If we did an entirely random pattern for the facçade,

if every plank was just generated

by some mathematical formula,

the risk is that two or three planks next to each other

would look similar enough

that your brain would see them as the same,

so we had to create this algorithm

that allowed us to fine-tune things

to make sure the architects

could look at the building from every angle

and they could tweak and adjust until it looked just so.

Narrator: With the shell working as one piece,

it was ready to take

the massive weight of the cladding.

All in all, there are 2,500 pre-cast rough stone panels,

weighing up to 6,600 pounds each

and spanning up to 13 feet.

Hanging them was going to be a challenge.

Dan: The facçade panels

are made from a concrete and reconstituted stone material.

They weigh an awful lot.

The facçade, the panels

weigh about the same as the wall that's holding them up.

The panels on a more vertical wall are smaller,

panels on the more sloping walls are bigger.

That presents another challenge

because the walls that are sloping and twisting

are working harder,

and the cladding hung off them is heavier.

So it's a sort of double whammy of challenge

that we had to overcome in the design.

Narrator: The anchoring points of the giant stone cladding

had to be seriously heavy-duty.

The engineers decided to set them in the shell

when it was first being poured,

letting the outer shell harden around them.

This, though, left no room for error.

Get it wrong, and the cladding wouldn't fit on the shell.

In the end, every anchor except three

was in the perfect position.

The exterior of the building was complete,

a testament to the Scottish landscape.

V&a dundee is proof that radical engineering

can breathe new life into a long-neglected area,

using the natural environment to redefine the urban landscape.

Hayley: The end result is a beautiful building

that is truly built to last,

as tough and rugged and as beautiful

as the Scottish landscape that inspired it.

Phillip: Dundee's falling in love with its waterfront again,

and people that come to experience v&a dundee

now have a new relationship with the river,

which has been suchúan important part of this city.

Narrator: Extraordinary engineering challenges

had been overcome to create the designer's vision.

Dan: I consider this to be a landmark project.

I find it fascinating

that people look at it as a piece of engineering

as well as a piece of art and architecture.

It's a visible piece of structural engineering.