Original subtitles

[Male narrator] How do you create a world-class museum

underground in a swamp?

[Lonnie] Every day the water got deeper

and they couldn't figure out how to do it.

[Narrator] Can engineers breathe new life

into a huge tower that has lain empty for 30 years?

[Sean] You realise that nothing is straight,

everything is enormous.

[Narrator] And how do you create an office block

where the floors hang perilously 100 feet into space?

It was possibly the most dramatic bit of construction

that I will ever see.

[music]

[Narrator] This is the age of the extraordinary.

[Hayley] It's like one of those insect-eating plants,

only enormous and white.

[Narrator] Where ingenious engineers

have unleashed unchecked creativity.

Now their secrets are revealed

as we discover the inside stories of their construction.

This is an incredible feat of planning and engineering.

[Narrator] To try and understand...

How did they build that?

During the series, some of the most thrilling

and ambitious building designs have been those for new museums.

The Museum of African American History and Culture

in Washington DC is one perfect example.

It uses the technology of today

to help us celebrate and understand our past,

while also planning ahead

for our environmental needs of the future.

On top of all of that, it just looks awesome!

[music]

[Narrator] America's capital city, Washington DC,

is home to some of the most recognisable

and historic structures in the world.

But if you take a short walk down Constitution Avenue,

you'll find an extraordinary new kid on the block,

albeit one that was a hundred years in the making.

[Lonnie] Everything about this was full of pressure.

Building a museum on the National Mall

within the sight of the White House,

but also exploring questions that Americans traditionally

don't want to explore.

[Narrator] A Smithsonian Institution museum

that tells the American story through the lens

of African American history and culture.

I remember my first time visiting.

It was like none other.

The building itself really resonates with me.

It's the perfect package for what's on the inside.

[Narrator] With an exterior wrapped

in a shimmering bronze lattice,

inspired by a triple-tiered crown from West Africa,

inside and out, this building is unique.

A triple inverted pyramid.

If it's complex to say, it must be complex to build.

[Narrator] 60% of the structure

would have to be built underground, in a swamp,

100 years after the idea for a museum was first conceived,

and facing a deadline to finish from the 44th president himself.

[Lonnie] He said to me, "Can you get this done

during my tenure?"

'Cause, as he put it, the brother wants to cut the ribbon.

[Narrator] This is the National Museum of

African American History and Culture.

So, how did they build it?

[music]

So the idea of the museum really began around 1913 to 1915.

That's when you saw celebrations of the 50th anniversary

of the end of the Civil War.

And they actually started raising money,

but then World War I broke out.

And then in the late '20s, the Depression hit.

And really, it flowed from there.

Every now and then, it looked like it might happen.

But then there was an assassination or war.

And so ultimately, it really wasn't until 2003

when it became real.

[Narrator] It took America's 43rd President, George W. Bush,

to push for the museum.

He invited Lonnie Bunch to oversee the project.

[Lonnie] I realised that if I could build this museum,

it would nurture the soul of all of our ancestors.

And that ultimately became too powerful to me to turn down.

[Narrator] The challenge is to come up with a museum

grand enough to sit on the National Mall,

which will set a new bar for

the public institutions of the future.

So we had an international design competition

with sort of 70 teams that really wanted to do this.

Some of the most famous teams in the world.

And then what we did is we narrowed it down to six.

[Narrator] The winning design comes from Sir David Adjaye,

now a celebrated architect responsible for

the Sugar Hill Housing Development in New York

and the Nobel Peace Centre in Oslo, Norway.

But in 2009, the Ghanaian-British architect

is still early in his career and is a relative unknown.

This will be his biggest project to date by far.

When we won the competition, I was incredibly euphoric.

I couldn't believe it 'cause I felt like it was a moment where

the sort of rocket ship took off.

[Lonnie] I was moved by his understanding of

how this had to be both centred in the culture,

but it had to symbolise more than one culture.

It had to be a welcoming place.

So ultimately, this soaring design

was really what got me very excited.

Suddenly it sort of dawned on me that, oh, my God,

we were gonna have to make this building

and that people were gonna look at this building and say,

"What the hell were you doing?"

Or, "What was this thing in your mind?"

And I just felt I couldn't fail.

[applause]

[Narrator] Then, just as the ground is broken,

Secretary Bunch rethinks the original design brief.

The initial plan had the history galleries on one level.

But I worried a lot about how can we tell the full story

in a way that would be engaging.

And then the exhibit designer, Ralph Applebaum,

said to me it would be better

if we had a tiered series of galleries

that would allow us to go deeper.

And that was one of those moments

where I really wrestled with, do I just let it go and say,

we have one floor?

But I thought about you only had one shot to get it right.

So let's do it.

[music]

[Narrator] The new plan is to fit

the 400,000-square-foot museum

onto a 5-acre patch of land.

Four floors will now be built below-ground, and five above.

The underground rooms will go down into the water table,

and will need double-thick concrete walls to stay dry.

Above ground, Sir David wants the exhibition halls

to be column free,

so the upper floors will be supported by just

four corner pillars carrying

the entire load of the building.

At the front, a 175-foot-long, super-sized porch

will house the museum's stunning entrance.

Finally, the 230-ton exterior facade will be modelled on

an upside-down, triple-layered corona,

inspired by a crown from West Africa's Yoruba culture.

Instead of digging down 20 feet,

now the builders need to go down 80 feet

to create the additional floors underground,

into a swamp.

[Lonnie] First I was sort of like, okay, fine.

I knew this is a swamp. We'll figure out how to do it.

But then every day the water got deeper

and they couldn't figure out how to do it.

This whole end of the Mall was actually filled in.

Um, it used to be where the old Tiber Creek

ran through here.

So if you dig 5 feet down, you hit the water table.

[Lonnie] And I remember thinking,

I'm gonna be known as the guy

that built the largest swimming pool on the Mall.

[Narrator] In order to hold back the water,

the foundations are redesigned to act like a dam.

Some of the excavation walls are as wide as I am tall

and then some.

So really some almost nearly 8-foot-thick walls down there.

[Nehemiah] A big challenge was stopping water

from getting underneath the foundations

and pushing the building up.

So crews had to extract water, almost 100 gallons a minute,

every day during construction of the foundations.

This water was replaced by a slurry mixture

of cement and sand injected into the forms

to then stabilise the site.

[Narrator] But pumping out the water could seriously undermine

the surrounding historic buildings and structures.

[Lonnie] We were on an aquifer of water.

And the bubble from the pressure from that water

is what kept the Washington Monument up.

[Zena] So it's all about making sure

that we monitor that water level

to make sure we were never drawing too much down,

and if we were, that we were able to recharge that water

to get that water table back up.

[Narrator] It costs over a million dollars

just to monitor movement on the Washington Monument.

But finally, in 2013, the foundations are safely in place,

and attention can turn to the underground exhibition halls.

Everything about this was a logistic challenge.

[Narrator] In fact, even planning how to get some

of the exhibits into the building

is proving far from straightforward.

I had spent time trying to find a railroad car

that would allow us either to tell a story

of the Pullman porters or segregation.

And a dear friend from my years

at the Museum of American History

had a railroad car out in Chattanooga, Tennessee.

So I went out there, saw this segregated railroad car,

and said, "That's powerful, I want to have it".

And then we realised that it was too big

to go into the building if it was enclosed.

[Narrator] It's 2013, and in Washington DC,

spurred on by President Obama,

work is underway building the National Museum of

African American History and Culture.

Secretary Bunch has found its first exhibit,

a segregated railroad car.

Now he just needs to get it to site.

We had to get special permission from Homeland Security 'cause

they were worried that it was so big,

somebody could blow it up and destroy a bridge

And we had to get special permission

which way to come into Washington.

And then we realised that it was too big to go into the building

if it was enclosed.

[Narrator] They decide they're going to have to put it

where the exhibit will live

and then build the rest of the museum around it.

[Lonnie] We actually put 500-ton cranes on the Mall.

We couldn't put them too close to the building because

they were too heavy for the walls.

But they were also placed on the main gas line of DC.

So the mayor of the District said, if you blow this city up,

you better get out of town.

We're lifting it up off the street, towering it over

and then putting it in place

where it was gonna be permanently.

And that moment told me, we're gonna pull this off.

[Narrator] The team's attention now turns to

the challenges of building the five storeys above ground.

Architect Sir David doesn't want the exhibition spaces

filled with any huge supporting columns.

[Zena] What's carrying the structural heft are four cores

that are composite. They're steel and concrete.

It was designed with these four cores coming up

out of this major foundation.

[Narrator] The four core pillars

will turn conventional building rules on their head.

[Zena] So if you think about these four cores that extend up

and then they carry these large girders that cantilever out,

and then the structure just hangs gently.

The other thing that allowed us to do

was have an almost completely column-free space.

[Narrator] The next challenge is creating the facade.

Designing it is one thing, but building it is another entirely.

Bronze cladding looks incredible,

but it also tends to come with an incredible bill,

especially on this scale.

[Narrator] For architect Sir David,

the bronze finish is non-negotiable.

Bronze seemed like a really powerful material to then use

for the skin of the building,

to create a weight and a dignity and a connection to history.

But also, there was a kind of way in which

the bronze of West Africa

would also connect to the bronze of the Mall.

[Narrator] Thankfully, they come up with a solution...

Bronze plating.

The actual physical material of the exterior of the building

is not solid bronze. [laughs] Yeah.

What the material is that you see is a cast aluminium.

It's lighter, you know, it has the durability of

a lifetime structure

that is necessary for this type of building.

[Narrator] Not only does it look beautiful,

it also makes the building more sustainable,

helping control the temperature inside.

[Brenda] The whole museum was designed

as a box within a box within a box.

The second box is the glass enclosure,

where most of the circulation and visitor activities happen.

And then the last box is the corona,

which helps reduce the amount of solar heat

that comes into the building.

[Narrator] Even the vast entrance space,

known as the porch,

contributes to the building's green credentials.

Without a porch, anybody waiting outside

to be in the museum in the Washington sun

would be burned alive. [laughs]

On top of that, we also have a fountain right at the front.

And when we get our summer breezes,

the air travels over the water

and creates a microclimate there

that is about 10 degrees cooler than what it is outside.

[Narrator] The porch, though,

does more than keep visitors cool.

[Zena] The reason why the porch is important is because

it has its roots culturally

in Southern African American sensibility.

The way African Americans in the South used the porch

truly as a space that welcomes.

So what we wanted to do was do, you know,

a really exaggerated expression of openness and column free,

and a welcome to all space.

[Narrator] Finally, on September 24, 2016,

over 100 years after the original idea was conceived,

President Barrack Obama opens the museum.

You had President Obama, President Bush,

the chief justice, you had the great John Lewis.

And it reminded me of America at its best,

when you saw Republicans and Democrats sitting together

to celebrate something they did together.

That, to me, was the power of that day.

[Brenda] I cried. It was uplifting.

It was, oh my God, you know, what we have done.

It was really, really, really emotional for me.

[Sir David] What drew me was really this incredible moment

in history to realise on the nation's capital

this profoundly important story that was missing

in the construction of America.

[Narrator] It's so popular,

it's the first Smithsonian museum

that needs a reservation and timed tickets.

This stunning futuristic structure not only serves

as a museum and memorial,

but a blueprint for how future institutions

can preserve and present collections

of national importance

in a unique, intelligent and sustainable way.

[music]

Designing an incredible building

isn't only about the shiny and new.

Taking an old building and giving it new life

beyond its original purpose can be every bit as rewarding

and even more challenging.

When this next building was originally designed

for the '76 Montreal Olympics,

it was so ahead of its time,

it missed its completion date by 11 years.

And then it lay empty for a further 30 years!

So, while it's never gonna win gold for speediest construction,

as an already iconic design re-imagined,

this project is way out in front.

[Narrator] In the era of regeneration,

the days of simply knocking a building down are over.

Instead, the idea is to repurpose and re-imagine,

no matter how far the original has fallen from grace.

There were birds nesting inside of the tower.

There was rain pouring in.

There was no water, no electricity, no nothing.

[Narrator] In Montreal, Canada,

that's exactly what they decided to do...

Take a tower that the city had seen as a failure for decades

and turn it into a shining swan.

It took four years

and pushed the architects and engineers to their limits.

One of the challenges of actually articulating

that vision was the actual construction site.

It was really like landing a spaceship

on an aircraft carrier.

[Sean] Once you get here, you realise

that nothing is straight. Everything is crooked.

Everything is curved. Everything is enormous.

[Narrator] But the result of all the innovative thinking,

ingenuity and collaboration

was the regeneration of an iconic building

on the verge of demolition.

[speaking French]

[Narrator] The largest inclined tower in the world,

designed as an avant-garde masterpiece, was reborn.

This is the Montreal Tower.

So, how did they build it?

[music]

[Narrator] The French-speaking city of Montreal

in Quebec, Canada

is an island on the St Lawrence River.

Nicknamed the City of a Hundred Steeples,

its mix of gothic, art deco and modernist architecture

has contributed to the city's ever-changing skyline.

One of the most important additions was the new centre

built to host the 1976 Olympic games.

Radical French architect Roger Taillibert

designed a futuristic sports village

with a stadium, velodrome and aquatic centre.

At its heart, he planned to build a tower

575 feet tall and inclined at an almost impossible 45 degrees.

[speaking French]

[Narrator] The Olympic arena was built in time

for the 1976 opening ceremony.

Unfortunately, its futuristic tower wasn't.

In fact, it took another 11 years to build.

By then, the project had run out of money

and the tower was abandoned,

lying empty for 25 years

until the park authorities

decided something needed to be done.

[Cedric] In 2012, the new administration

that was at the Olympic Park was there and said, okay,

we are at the turning point right now.

We need to stop waiting for the government

to say and to do something about the park and the stadium.

We need to show the people what are the possibilities

of that equipment.

[Narrator] They decide to turn

the world's tallest inclined tower

into a state-of-the-art $200 million office block.

60% of its curved concrete exterior

will be replaced with 3 miles of flat glass,

forming a curtain wall.

Inside, the building will be opened up to create 14 floors

of modern, open-plan office space.

And the rooftop bar will give visitors

uninterrupted views of the city

to celebrate this landmark once again.

But to pull this off, the team has to calculate

how to work with the existing structure...

No easy task.

What we realised on this project is that

not one floor would be the same,

not one facade would be the same,

and that standard methods of doing the work

would not be possible for us.

[Narrator] Despite the obvious challenges,

in spring 2015, work starts on the building.

The main job is going to be creating the glass curtain wall,

which involves removing 450 enormous concrete panels

that cover over half the tower...

and then replacing them with 3 miles of reinforced glass.

All of that requires a very special crane.

[music]

[speaking French]

[Narrator] The 600-foot-high crane,

nicknamed The Giraffe,

is so tall, it's brought to the site in pieces.

And the challenge then is finding a space

to put it together.

Actually, it's a bit complicated to find

the optimal position.

We realised that we needed to go through the sports centre,

and that also we were going to go through the roof.

That was actually a pivotal moment for us.

I still remember that meeting when we had to tell them

that we're going to go there.

The reaction wasn't, of course, too optimistic.

They told us it was impossible.

[Narrator] After some delicate negotiations,

they agree to close part of the sports centre,

and a hole is punched in the roof for the crane

to go through and up 600 feet in the air.

[speaking French]

[Narrator] A 700-ton mobile crane is brought on site

to lift the huge sections of tower crane into place...

starting with the base unit,

which is slowly and very carefully lowered through

the Olympic stadium roof.

[speaking French]

[Narrator] After 10 long days of precision manoeuvring,

the tower crane sections are assembled.

Working at such extreme heights is incredibly time consuming.

The crane operator takes half an hour just to climb to his cabin.

It's not a job for the faint hearted.

[speaking French]

[Narrator] It takes nerves of steel and a steady hand

to manoeuvre the crane into position

and lift the concrete panels hundreds of feet below.

[Sean] These panels are all anchored to the structure.

Some of these are almost 8 metres high

and weigh 5 tons.

[Narrator] Before they can be removed, every anchor point

has to be cut through with a specialist diamond wire bandsaw.

[speaking French]

[Narrator] The construction team on the Montreal Tower

finally finish removing all 450 concrete panels

from the exterior.

Now they have to prepare the tower

for the glass curtain walls that will replace them.

[Pierre] [speaking French]

[Narrator] As work begins on fitting the glass panels,

they're stress-tested to make sure

they're strong enough to deal with the extremes

of Montreal's weather.

In a typical office tower,

the curtain walls are vertical.

In this case, they were on an angle,

which means they're almost like a roof.

And when it rains and snows, they don't react the same way

as when there are typical office tower.

So in order to be able to have a quality curtain wall,

different tests were done...

Wind tests and rain tests... To make sure

that there was no infiltration.

[Narrator] The tests confirm that the glass panels

are watertight and wind resistant,

so installation continues.

But at the observatory on top,

engineers face a new challenge.

[Sean] The problem was with the south facade,

because that's the facade where you have the 45-degree angle.

So the cranes don't have access,

you have all the cables that hold the roof.

And since you're working on the 45-degree angle,

well, the only way to get there is with the workers on ropes.

[Narrator] It's 2012, and in Montreal, Canada,

a team of specialist steeplejacks is brought in

to work from fixed lines at extreme heights.

They begin installing the glass panels one by one.

But it's not easy.

[speaking French]

[music]

[Narrator] Two and a half years after work began,

four decades since the tower was first scheduled to open,

the facade is transformed

with over 3 miles of reinforced glass curtain wall.

A thoroughly modern reinterpretation,

it's now fit for the 21st century.

When you transform and re-clad a building,

it's like giving new clothes to a person.

And in a way, you give a new identity.

[Narrator] After decades of neglect,

overcoming adversity and controversy,

Montreal's Olympic Tower re-opens in 2018.

Now home to hundreds of office workers,

it combines creative workspaces

with some of the best views in town.

[speaking French]

[Narrator] Completely reimagined and repurposed,

the tower stands proud once again,

reaffirming its place on the Montreal skyline

for now and for generations to come.

[music]

We head 3700 miles northeast now to Norway,

a country I've learned loves nothing better

than impossible challenges of design and engineering.

Now, this next building was not so much a construction project

as a super-sized game of precision Jenga

played with five 460-feet-long,

3-storey-high building blocks

that project LCD art installations

from their massive 100-foot cantilevered overhangs.

What?

Look, Norway gets cold.

And this is one building that is totally ice cool.

[Narrator] The idyllic Oslofjord,

with its dense forest and mirrored surface water,

reaches through Norway up to the shoreline of Oslo,

the country's capital,

one of the happiest places on earth.

It's also one of the most exciting,

especially when it comes to striking buildings.

So when Norway's energy giant, Equinor,

was looking to build a new HQ there,

it was always going to be something special.

But what designers came up with was extraordinary.

The result is mind blowing.

[Narrator] A building that could withstand temperatures

of up to 95 degrees in summer and minus 13 in the winter.

It takes a lot of precision engineering

to make it look this casual, but work so well.

[Narrator] It had a roof where no two pieces of glass

were the same.

We weren't sure that we could manage to build

the glasses that the architects had drawn.

[Narrator] Five gravity-defying,

horizontally stacked skyscrapers that hang into space.

This giant stack of boxes and slopes

seems to teeter dangerously over the street.

[Narrator] This is the Equinor Building in Oslo.

So, how did they build it?

It's Norway, 2009, and Equinor,

one of the country's largest energy producers,

launches a competition to come up with an extraordinary design

for an eco-friendly HQ.

Forty practices enter, including local architects A-Lab,

responsible for Oslo's iconic Barcode District skyline

In an industry badly hit 10 months earlier

by the 2008 financial crash,

there's a lot riding on their pitch.

It was a huge project for us

and an important competition to win.

[Narrator] The winning design is to be built

on the site of the old Oslo Airport

on the Fornebu Peninsula.

Opened in 1939, in the Second World War

it was taken as a strategic Luftwaffe base.

Post war, it became Oslo's primary international airport

before finding itself too small for modern airliners.

In 1998, it was closed down.

This is the last fjord site as it was then,

an open site with a great aspect

towards the Oslo fjord.

[Narrator] It's an incredible location on the water's edge,

and the architects have come up with a stunning design

that must overcome many challenges.

The ground is unstable,

so they will need to dig deep and strong foundations

to support the building.

The central hub will be placed in a huge atrium

that will be built around four giant concrete cores

and wrapped in a curving propeller-shaped glass roof.

But planning restrictions limit how high they can go,

so they will build out sideways,

stacking five horizontal office blocks at angles,

with the top three positioned so they hang perilously into space.

The result, a 9-storey building

that resembles a starfish from above,

which allows them to minimise how much ground space

the offices cover

and maximise the space for an impressive park beneath.

Stacking the blocks will also make the most of

the spectacular location on the edge of Oslofjord.

Everyone gets this beautiful view.

Whether it's diagonally or straight out of

the ends of the building,

you utilise these views in every single direction.

[Narrator] It does everything the client's looking for

and more. And in 2010,

A-Lab's design wins the competition.

This is a mind-blowing feat of both engineering and planning.

[Narrator] Early in 2011, work starts to clear the site.

The catch, though, is that the client needs the new HQ

built and operational in just 20 months.

[music]

[Narrator] It's 2011, and in Oslo, Norway,

the teams are starting work on a new HQ

that has to be finished in 20 months.

From the beginning of the project,

no one really realised the incredible requirements

that it put everyone under.

This is the largest project we have ever built

and it was the shortest construction time. [laughs]

[Narrator] That's not the project's only challenge.

They need to create over 200,000 square feet of floor space.

But planning restrictions mean they're only allowed

to build to 120 feet.

A tower was out of the question, quite simply.

[Narrator] To solve the problem,

they turn to an engineering principle called a cantilever.

The actual physical building

and construction of the cantilevers

was therefore one of the most important elements of it.

[Narrator] This allows huge sections of the building

to be supported at just one end.

[Corina] In a normal building,

weight is distributed evenly across the foundations.

But this building is like an unbalanced seesaw

pushing down on one side and pulling up on the other.

These opposing forces are going to put the foundations

under a serious amount of strain.

[Narrator] If the foundations aren't strong enough

to counteract the combined forces,

the huge office blocks will fall.

The team has to make sure that doesn't happen.

The excavation work was significant

and went a long way down into the bedrock.

The preparation involved also stabilising parts of the rock,

which is quite a weak Oslo slate, as it's called.

[Narrator] In order to strengthen

the looser slate sections,

they will have to drive piles deep into the bedrock

before reinforcing them.

Despite the tight schedule, this is one job that can't be rushed.

The winters in Oslo can see temperatures dropping

to minus 10 degrees,

and if there's one thing uncured concrete doesn't like,

it's the cold.

[Peter] We started here in January,

and that was a very cold winter that first year.

So that we had to mount the quite big areas

without actually pouring concrete.

[Narrator] By spring, they're ready to take on

their next challenge...

Counteracting the extreme forces from the cantilevered design.

This is achieved by creating an enormous skeleton from steel,

which will carry the forces from the huge blocks, or lamells,

into the centre,

where they will be channelled down the four giant cores

to the foundations.

Steel construction on this scale

is not something the team has done before.

[Peter] This is the first time ever build

construction like this.

And, uh, so we learn a lot about steel constructions

that are more complicated than this, uh,

this building than other normal buildings.

[Narrator] With time of the essence,

they know they have to find ways of speeding up the build.

The contractor immediately saw that prefabrication

was the only way to create such a building so fast on site.

[Narrator] They decide a whopping 1600 elements

can be made off site.

But that involves precision planning

to keep things on schedule.

What was incredible about coming to site

was having to deal with different stages

in the construction process simultaneously.

The fit-out of the lower lamells was happening

while the steel truss for the top lamell

was being hoist into position.

[Narrator] The steel elements arrive from factories

like a pre-made monster Erector set.

Once on site, each piece needs very precise welding

to create the huge framework.

To stay on schedule,

they brave temperatures frequently below freezing.

But welding also doesn't like the cold

as it can leave it weakened.

It's yet another headache for the team.

We build the big tents on site there

to try to get the climate because, uh...

there was huge welding job.

And that has to be accurate,

and we have to control every part of the welding process.

[Narrator] Now they need to carefully put

each of the hundreds of pieces in place.

This project too calls for a huge crane.

It takes 54 trucks under police escort

to bring the crane in pieces, totalling 1250 tons.

Once there, they need a vast 2000-square-feet area

to build a large enough base to put it on.

The crane could actually lift... I think it was 60 tons

on 120 metres from the centre of where it was standing.

And without that crane, we couldn't be able to assemble

this building in that short construction time.

[Narrator] Time may be running out,

but the main structure is at last beginning to take shape.

[Charlie] The biggest day for us

was lifting the last piece of the truss onto the top lamell.

Strangely, the last piece was the one furthest away

from the production area, on the other side of the building.

So the crane had to lift up 100 metres

and over 100 metres.

It was possibly the most dramatic bit of construction

that I will ever see.

[Narrator] It's a precision job for the crane operator,

dropping that final piece in exactly the right place.

The next challenge is creating the roof that will wrap around

the central atrium.

To maximise a sense of openness,

the architects want to use the fewest columns to hold it up.

So they come up with a very special glass structure.

So it's a bit like a soap bubble,

if you can imagine creating that soap bubble

and then twisting it.

The soap bubble description refers to the super clever way

a thin layer of soapy water will stretch to cover an area

and then contract to the minimum size it can without bursting

[Narrator] The pioneering architect Frei Otto

was the first person to experiment with this idea

in the 1960s.

Given a set of fixed points, he noted soap film will spread

to offer the smallest achievable surface area,

which he most famously used for Munich's Olympic Park.

This technique means the roof will weigh

the least possible amount

and reduce the additional load on the supports.

Perhaps more importantly, though,

it also allows them to create something really unique...

but untested.

It was a risk because this hadn't been done before

in Northern Europe.

[Narrator] The twisting structure means that

no two pieces of glass or steel frame are the same.

So constructing it is like

piecing a huge jigsaw puzzle together at great height.

None of the glasses are actually curved,

but all the nodes on the steel

and all the glasses have a different shape.

[Narrator] The roof also needs to be designed and engineered

to cope with snow.

Oslo gets a lot of it.

And that will create a huge amount of weight

pushing down on the glass.

The engineers have to run computer models

to perfect the design

and ensure the roof will be able to stand up to

the worst of Norway's winters.

The result is both beautiful and strong.

[Charlie] The total snow load in the corners of the glass roof

is the equivalent of an articulated truck

being parked on that roof.

[Narrator] The ingenuity does not stop there.

For decades, Norway has led the charge towards renewable energy,

with most now provided from the rivers

that cascade into its fjords.

And Oslofjord on the building's doorstep

provides them with a completely different green energy solution.

So a major part of the energy efficiency of the building

was also the use of the fjord

to both cool the building in the summer

and to help warm the building in the winter.

[Narrator] The average temperature of the water

is 48 degrees,

so piping the water into the building

will help bring the ambient temperature either down or up

to a comfortable level.

Completing the work goes down to the wire.

And the engineers know that missing the finish date

would incur huge financial penalties.

A final push leaves them within a whisper of the agreed date

in October 2012.

We were supposed to hand it over on a Friday,

and it was very close.

But, uh, we agreed that we could have the weekend.

So we handed it over on Monday and everybody was happy.

[laughs]

[Narrator] Just 20 months after work started,

this incredible cantilevered office building,

wrapped in thousands of unique glass panels

and situated on the banks of the glorious Oslofjord,

was ready to take its place

amongst the other iconic Oslo architecture.

[Peter] Oh, I remember that last weekend.

One of the construction guys

actually stood in the staircase with a trumpet, playing.

Yeah, everybody was happy, and it was euphoric to be able

to hand it over, that construction in time.

[Charlie] It was only when we stood back

and looked at the final product

that the feeling of accomplishment as a team,

together with the contractor and all the other consultants,

really sank in. It took some time.

[Narrator] Constructed under huge time pressure,

this incredible award-winning project

has created an office environment unlike any other.

It's a building that gives everyone inside

an awe-inspiring view of the fjord.

And everone outside is blown away

by its staggering, eye-catching looks.