Original subtitles

- [Narrator] We are surrounded

by extraordinary feats of engineering

constantly pushing the boundaries of what's possible

- Without engineering, there'd be no modern world.

- Gigantic cities, amazing infrastructure and

ingenious inventions

- Engineering is the key to turn dreams into reality.

- To reach these dizzying heights,

today's technology relies on breakthroughs

made by ancient engineers.

- It's mind boggling how they did this.

- How did early civilizations build on such a scale?

- They raised the bar for construction in a way

that no one thought possible.

- The sheer engineering ability it is in itself impressive

- By defying the known laws of physics

and daring to dream big.

They constructed wonders of the world from gigantic pyramids

to awe inspiring temples and mighty fortresses.

All with the simplest of tools.

- Can you imagine the skills people would have needed

to build like this?

- Now it's possible to unearth the secrets

of the first engineers.

- They managed to construct edifices

that has survived the ravages of time

- And reveal how their genius laid the foundations

for everything we build today.

[dramatic music]

In the modern world,

structures dedicated to God still dominate city skylines.

Built with no expense spared,

by all the world's major religions across the globe.

- They are a feat of engineering.

They are images of heaven.

- Amazing mosques, temples, synagogues and churches,

Houses of the Holy.

- The impact they were designed to have

is utter awe and wonder

- But these white hot modern wonders rely upon earlier

breakthroughs.

The engineers who constructed them using knowledge

and skills built up over thousands of years.

Lessons hard won, ancient engineers

battled deadly collapses, earthquakes, fire

and warfare to create amazing devotional buildings

in honor of their gods.

Building for God reached a high point in the middle ages

when a new engineering movement emerged

changing the rules forever.

It aimed to use engineering and architecture

to create a glimpse of heaven on earth.

And it led to the creation of some of the most beautiful

and spectacular buildings ever seen.

Gothic cathedrals

- Gothic cathedrals are not only the most spectacular

buildings of their age, I think there are among

the most spectacular buildings of all time.

- They are symbols of our civilization.

They are symbols of human achievement.

We've never really seen anything like it again.

- Taking centuries to build, reaching soaring Heights

they feature intricate walls, ceilings of solid stone

carved like spider silk and vast stained glass windows

seeming to float in midair.

- When they go in, people's jaws hit the floor

and your eyes go up to the roof.

I actually think your heels might come off the ground a bit

as you're transported up to the heavens.

- You are taken out of the everyday world

and you encounter something of the divine.

- The construction of Europe's Gothic cathedrals

was one of the pinnacles of human achievement

- We needed an engineering revolution in design

to be able to create that very characteristic Gothic style.

- These buildings have endured

as a lasting symbols of their age

- To this day, Gothic cathedrals are one of

the most outstanding engineering achievements of all time.

- One of the most iconic is Notre Dame.

Built in the heart of medieval Paris,

many believe it's one of the crowning achievements

of the Gothic movement.

Mainly constructed between 1163 and 1250,

it set out to surpass all cathedrals that had gone before,

to push the technology of the day to its limits,

taking great risks

and completely reinventing how a church could look.

- There was this challenge of massive construction

that would be naturally heavy but then introducing elements

that made them like they lighter than air.

- How could it be done?

- How do you build high?

How do you stop the walls falling down?

How do you stop the roof falling down?

- The solutions arrived at in Notre Dame were world changing

and they've stood the test of time.

Innovations built into the fabric of the cathedral

were copied again and again in structures

across Europe and beyond.

So what are the engineering secrets

that made these spectacular new marvels a reality?

To create Gothic, medieval architects

would need to rewrite the rule book

and challenge engineering principles laid down

in the earliest churches.

These simple structures had their roots

in a building from the pre-Christian world.

The Roman Basilica.

- The Basilican form is not a religious building

in origins at all.

It's legal building or a law court.

- A Basilica was always a predictable

rectangular shaped building.

It would have a nave and two or more aisles at each side,

a high roof vaulted with a half dome and a raised tribunal

that Roman tribunes would have stood upon.

Many of the features that would be found

in the cathedrals and churches that would follow.

Essentially the Gothic cathedral did originate

from the Roman Basilica.

- From there we are transept and then we are at towers.

So it all evolves throughout the next two, three, 400 years.

- Basilicas like the cathedrals that came after them

were usually built in the very heart of a town or city,

prestige buildings.

- What happens is that these basilicas are taken over

by the church.

The Basilica form is then reproduced again

and again and again in early churches.

- In the fourth century, dramatic events in Rome

would speed up the transition from Basilica to church.

Inspired by a series of religious dreams and visions,

the Emperor Constantine made Christianity legal.

10 years later, it became the official religion

of the Roman empire.

By the sixth century, the Western Roman empire had fallen.

What survived lay in the East.

It came to be known as the Byzantine Empire

and it straddled Europe and Asia.

Its capital was Constantinople.

The Byzantine empire was the most important economic,

cultural and military power in Europe

leading the world in mathematics and engineering.

In 532, the new emperor Justinian wanted to signal

his prestige with a spectacular Christian Church.

It would be known as the Hagia Sophia or Holy wisdom.

Justinian imagined a vast interior,

topped by a huge and dazzling dome.

And that presented a major engineering challenge.

- They wouldn't have had any idea

whether that building would have worked

because there's nothing else like it.

They're stepping off into the unknown

- Could such an audacious design be made a reality?

For those charged with building it,

the pressures would have been immense.

- I can imagine the construction site at the Hagia Sophia

was incredibly stressful

because you were embarking on the unknown.

- With a planned height of 183 feet,

and a footprint of nearly 65,000 square feet,

the Hagia Sophia would be a huge building.

- Two things happen when you increase the height

of the building.

One of them is that you expose the building

to a lot more wind force.

The other thing is the building itself weighs more

and that increases the loads on the foundations

that are underneath.

- Workers would need to dig deep foundations

into thick bed rock with limited tools.

Today mechanical excavators dig foundations

which are then reinforced with concrete.

In 2014 the Wilshire Grand Center in Los Angeles

took foundation construction to a whole new level.

It required a single gargantuan slab of concrete

sufficiently robust to stabilize

the building in an earthquake

calling for a lot of concrete to be poured in one go.

Engineers choreographed 2000 truckloads of concrete

pouring continuously for 20 hours

breaking the world record

at the time for the largest uninterrupted pour.

When completed, the foundations were 18 feet deep

and weighed a mighty 84 million pounds.

They support the tallest building in Los Angeles.

An office and hotel complex reaching 1099 feet

In sixth century Constantinople, the Emperor Justinian

had started his own record breaking building,

the Hagia Sophia.

To ensure success, he turned to two

of the greatest geometers or engineers of his day

Isidore of Miletus and Anthemius of Tralles.

Before they could construct the massive dome,

they had to solve the geometric problem

of placing a circle on top of a square.

- What domes tried to do is flatten.

So they push outwards.

So what you do in that case is you have to tie the base

of the dome together so the forces are resisted

and only vertical loads go down the walls

'cause it's the horizontal loads

that would push the walls over.

The architect's designed for massive piers

to stand at each corner of the square.

On top of the piers, they built four arches

and fill the spaces between with masonry

to create curved triangular shapes called pendentives.

These combined with the tops of the arches

to create a strong base for the dome.

The engineers recruited 10,000 workers to get the job done.

And in 537 AD, after little more than five years

construction time, it was complete.

The structures dome towered over the city.

From inside the dome appears to float

above a ring of windows.

These led in a flood of celestial light

to illuminate the nave below.

At the time, this was the world's largest interior space

and the most complex building yet constructed.

Isidore and Anthemius had solved the problem

of dome architecture in a stroke of engineering genius.

But it wasn't long before the Hagia Sophia faced disaster.

- Despite Justinian having the best technologies

available to him at the time, he is still at the mercy

ultimately of the gods in the natural world

- In 558AD, a major earthquake struck Constantinople

The dome failed collapsing in ruins.

It was soon rebuilt in a taller and stronger form.

Over the centuries, earthquakes have continued

to inflict damage on the Hagia Sophia

but this magnificent structure still stands today,

a landmark in the history of engineering

- It shows the fundamental strength of the principles

that they are applying that despite earthquake,

despite war it's still there.

- Even modern day engineers struggle

when faced with the destructive power of earthquakes.

In Kobe Japan in 1995,

a quake measuring 7.2 on the Richter scale wreaked havoc

toppling countless buildings and an elevated freeway.

In total that caused $100 billion worth of damage.

- What we've learned from recent earthquakes like in Kobe

is that every single earthquake is different.

It has its own fingerprints, if you like.

Every time an earthquake happens,

engineers learned something new

and they apply it on the next building.

- Most buildings are designed to support a vertical load

flowing down through the walls

but not a horizontal load pushing sideways.

And in earthquakes it's often the horizontal forces

that do the damage.

- When an earthquake hits a structure,

the structure is going to be shaken in a sideways motion

and these forces can also push the building up

and down as well as sideways.

And that was kind of what makes it so chaotic and intense.

- That change in direction which cause forces and stresses

in the building and cause things to break

- One high-tech solution is to protect a building

through base isolation.

Constructing it on giant flexible pads

made of steel and a rubber

or pits of ball bearings and Springs.

When a quake strikes, the isolators vibrate

but the building itself should remain steady.

Incredibly, a similar solution was developed

by Chinese engineers 2,500 years ago.

They designed a bracket system called dougong

that can even survive modern day shake tests.

The dougong is a masterpiece of joinery,

a series of interlocking beams,

each cut to precise measurements.

When compressed under the heavy roof, the system

is very strong yet remarkably flexible.

None of the individual pieces are fixed or glued

and the supporting columns are also free standing.

so the building moves with a quake

And it's worked

Many ancient Chinese buildings have survived

numerous earthquakes.

This principle underpins another

modern earthquake-proofing technology.

- Another way is to put a damper inside the building.

When the earthquake pushes in one direction,

the dumper moves in the other direction.

So it counteracts the forces.

- Taipei 101 has a damper system featuring

a mighty 728 ton pendulum.

It's made of 41 layers of steel plates

suspended by eight steel cables.

Below are 16 hydraulic viscous dampers

eight slanted and eight level.

The pendulum moves to counteract strong winds

and even earthquakes reducing building vibration by 40%.

- It's incredibly impressive.

When you think about it's a very simple use of physics

to protect a building but incredibly effective.

- There's no doubt these engineering developments

have helped tall structures survive earthquakes

In medieval France, a different kind of seismic change

was about to occur.

This time it wasn't earthquakes that posed a threat

to traditional churches

but the ambition of a new breed of engineer.

Leading the way, Abbot Suger.

Close to the King of France and to the Pope,

Suger was an influential figure of his age.

His prestigious Abbey Saint-Denis,

stood on the outskirts of Paris,

but was in dire need of renovation.

Suger make-over plans called for nothing less

than an engineering revolution.

Until now the options

had been limited for European churches.

Most were built in a bulky and squat style known

as Romanesque, heavy roofs supported by thick walls

with small windows casting very little light

into cramped interiors.

Suger believed a new form of engineering

could make a new kind of church possible.

His ultimate goal to get more heavenly light into his Abbey.

- Christ and God was seen as lux, light,

the light of the world.

And so the more lights you could get into your building,

the closer you could get man to God.

- Light would help create an experience of heaven on earth

inspiring religious fervor in church goers.

But how could Suger develop the engineering tools

to achieve this?

It wouldn't be easy.

- The simple problem of getting light

into a massive building,

is that you need to make holes in walls

and yet those walls support the roof.

So to put windows into walls you need to make sure

that those walls themselves on not weight-bearing.

- Suger needed a new approach to construction.

In the process he'd kickstart what would become known

as Gothic architecture.

Work began on Saint-Denis around the year 1135.

The first engineering innovation was the use

of the pointed arch.

At this time, most churches had conventional rounded arches

weight from above was distributed out to the sides.

Thick walls were required to resist these forces

but to achieve his new vision, Suger needed tall thin walls

with large windows.

The pointed arch distributes weight downwards not sideways.

So heavy walls would no longer be necessary.

A second innovation helped reduce the load even further.

Ribbed vaulted ceilings work like a skeleton of stone

thick supporting ribs with a thinner stone skin

filling the space between.

- What the narrowness of those ribs actually does

is allow you to transfer more weight from above

and it takes it directly downwards

rather than pushing the walls out.

- Revolting was extremely revolutionary.

The excess tension was taken down

into your small slender piers so everything could be lifted

upwards, could be lifted outwards. and the tension

was taken down once without just collapsing in.

- It's effect was to make the vault or ceiling much lighter.

- You have these thin ribs going up into the ceiling

and peeling off in wonderful curve.

So they almost looked like the bowels of a tree,

very very delicate and yet so good

at supporting immense weight

- But even with a reduced load, some sideways pressure

pushed against the walls.

So Sujer and his architect made use of the feature

that now truly defines Gothic architecture.

The flying buttress

- Flying buttresses are sort of the epitomy of Gothic

which create a sort of skeletal structural cage

around the exterior that holds up

this light airy structure within it.

Piers or buttresses, outside the building

are connected using sloped fliers.

These take horizontal forces

and redirect them to the ground.

They took the weight, which was pressed outward

on the walls and they absorbed it down

to strong buttresses on the outside

- Flying buttresses are thin and separated

from the building so they don't block out light.

And with thinner walls,

it was possible to engineer huge stained glass windows

on a monumental scale.

Just as Abbot Suger had intended,

they allowed daylight to flood in.

- The link between light and the divine

is actually a very ancient idea,

but the Gothic architects were the first ones

who managed to bring it into the construction

of immense buildings in a coherent way

- Completed in 1144, the rebuilt Abbey of Saint-Denis

was an engineering triumph.

Here for the first time in one place,

were the three defining elements of Gothic pointed arches,

rib vaulted ceilings and flying buttresses.

- What Suger did at Saint-Denis was so spectacular

but it becomes a blueprint for cathedrals

across Northern Europe.

- The result of the innovations at Saint-Denis

was spectacular.

A gravity defying lightness, soaring ceilings,

a delicate house of cards, suffused with light.

The success of this new Gothic engineering

lay in moving stone from inside to outside

leaving the interior open and uncluttered,

a lesson modern engineers haven't forgotten.

800 years after Saint-Denis, a new building in Paris

would once again turn the world upside down.

The Pompidou Centre opened in 1977

It's the first example of a modern inside out building.

All of its plumbing, electrics and air con systems

have been moved to the outside of the structure

where they're celebrated in bright colors.

Just as at Saint-Denis,

The motivation was to create more space inside.

Engineering driving new forms of construction.

In 1986, the Lloyd's Building in the city of London

pulled the same trick shifting services

to the exterior, but this time upward

creating cavernous interiors filled with light.

- This is sort of like putting your skeleton

on the outside of your body

so that you can see how your body works.

You create some interesting architecture,

engineers love it, but not everybody does

- Never again, would an architect need to hide

the working guts of a building.

- I really love inside out buildings.

And what I really like about places like the Pompidou Center

is that you can really see how the structure works.

- Groundbreaking engineering sets trends

that inspires imitation.

And in 12th century Europe,

this was certainly true of Saint-Denis.

Suger's New Abbey had caused a stir.

It's adventurous style would inspire

one of the greatest cathedrals of all time

and a pinnacle of French Gothic architecture, Notre-Dame.

The Bishop of Paris, Maurice de Sully was determined

to outdo his rival Abbot Suger.

Like Saint-Denis, Notre Dame Cathedral

was no longer fit for purpose and De Sully

wanted the latest engineering for his own renovation.

- It really was a cathedral race.

- There's almost certainly a one-upmanship

that's going on all over North and Europe.

Threw down the gauntlet to his cathedral builders.

The challenge, construct a church

in the style established at Saint-Denis, but on steroids

- What they were doing at Notre Dame is essentially

supersizing what had just been achieved at Saint-Denis

And it was very audacious to actually say, we can do more.

The architects of Notre Dame,

they wanna pick it up and they wanna push it even further.

And they want to build a church bigger

than anything that had been built before.

Work began on the reconstruction of Notre Dame in 1163

when its cornerstone was laid

it was a colossal undertaking several hundred workers,

a building site full of noise and dust, the smoke

and fire forges, the rasp of carpenter saws,

stone dust thick in the air as masons cut and carved

and polished.

- It's bringing in so many people to do the work

that it helps to transform the economy of Paris.

- The architects of the time were master masons,

men of vision and skill who use geometry

to create sophisticated patterns in stone.

Once foundations were in place, engineers could make a start

on the walls of the church.

De Sully wanted taller walls

so much bigger flying buttresses would be needed

than at Santa-Denis.

As the walls soared higher, scaffolding became necessary.

It was hung as a section from the walls and lifted higher

as the wall height increased

Building cathedrals was an incredibly dangerous process.

You're thinking about carrying blocks up immense heights

in an age before they have proper modern scaffolding

- They need to be brave.

And there are tragedies there are accidents people die

- But how did medieval builders haul huge rocks

high up in the air?

Today city skylines are dominated by cranes

mechanized equivalents of a tool invented

around 1700 years ago, the windlass.

This early form of winch was designed to lift heavy weights.

Medieval engineers adapted it to create a crane

attaching the winch to a large wheel.

Like some giant hamster wheel,

the human inside provided muscle power

to efficiently lift heavy loads of stone.

Placed high in the building,

it was used to lift all the elements needed

for the roof and vault.

- The vaulting was very important

because it was something beautiful to look up to.

That was the whole point of the Gothic cathedrals

so your eyes were raised up to the ceiling

so it needed to be beautiful.

- Construction of the roof and the vault

was one of the most dangerous stages of cathedral building.

And even today roof construction

can be an engineering nightmare.

In 2003, a new terminal open at Charles de Gaulle Airport

15 miles Northeast of Paris,

Terminal two featured a futuristic concrete tube

cut through with windows designed to awe inspiring

but sometimes the vision of architects

conflicts with on the ground realities faced by engineers.

- Quite often you get this battle of form versus function.

And as engineers, we're obviously trained

to come at this from a very pragmatic approach

and the artistic nature of it comes second to that.

- 11 months after opening a section of roof collapsed

The disaster killed four people and injured more.

An investigation revealed the main roof beam

and concrete reinforcing weren't strong enough

and this contributed to the collapse.

- The tragic collapse of the

Charles de Gaulle Airport building

just shows how critical it is for engineers to be able

to deliver the architect's vision safely and securely

- At Notre Dame, the engineers and builders

toiled for decades to realize the dreams

of the Bishop of Paris.

By the year 1260, Notre Dame was largely complete.

It had taken around a century to create this

remarkable structure.

The rebuilt cathedral soon became a symbol of Paris

and even of France itself.

[music]

- Notre Dame is one of the first supersize Gothic cathedrals

that then came to dominate Europe.

It was proof that the idea is explored in Saint-Denis

actually worked and could be applied across the board

- That is where the real engineering feat is

in these Gothic cathedrals.

It's just pushing the style and the technology

as far as it can go.

It's pioneering rib vaults, colorful and gigantic

rose windows and staggering height

made this cathedral a new wonder of the world.

If I today, I'm in awe of it goodness knows how

people must've felt all the way back

in the 12th and 13th centuries.

- I think that going into Notre Dame would have been

mind blowing for people in the 13th or 14th centuries

to see a building the likes of which had never been achieved

before you'd go in and the walls were pierced with windows.

The whole building was flooded with light.

The vaulting was inconceivably high.

It would have been a profound memorable physical experience.

- The outside of the cathedral was equally impressive

not least thanks to its spectacular flying buttresses.

These had never been attempted on such a scale before

and came to define cathedrals from the peak

of the Gothic era.

Some modern architects still incorporate flying buttresses

into their buildings

but this is often more about style than necessity.

- With the advent of steel and reinforced concrete

in the 19th century, what we're able to do

is resist tension forces.

They didn't have that option in the Gothic cathedrals.

- Today's engineers have access to materials

that can stretch or resist tension

in ways their medieval ancestors could only dream of.

Thanks to the strength and malleability of concrete

and steel, buildings can now soar to the heavens

without any extra support structures.

- Materials like steel which can have high tensile strength

means that we have much more freedom

in terms of how we design a building

- And human nature means striving to build ever higher.

[music]

In the middle ages, Notre Dame launched a race for height

At 226 feet tall, it was undoubtedly impressive,

but inspired by the achievement across Europe,

New cathedrals would go on to smash the record

time and time again.

- They were building greater higher, wider, taller

buildings all trying to outdo and get theirs finished first.

- In 1311, Lincoln cathedral became the tallest building

in the world at 525 feet.

It was the first to surpass the height

of the Great Pyramid of Giza and held the record

for 238 years until its Spire collapsed.

In the year 1225, Beauvais Cathedral

was sent to take up the mantle

but something went terribly wrong during construction.

- It collapses.

What happens at Beauvais is a collapse.

Engineering experts think that cathedrals, columns

or piers were simply too slender for its great height.

Over time, the weight of a building

can cause mortar to shift and crack

which can in turn, move arches and columns

and eventually bring the whole thing crashing down

In 1573, Beauvais collapsed a second time.

Stones began to fall during a service.

The congregation rushed out

Miraculously, nobody was killed.

Today, modern braces may be the only thing

keeping Beauvais cathedral from falling down.

- I think what happens at Beauvais is an example

of really just pushing high Gothic to its limits.

You can put your trust in God and the skills of your masons

but when you just try to push too far

and too hard things start collapsing

- The passion to build ever bigger ever more beautiful

had pushed Gothic engineers to the limits and beyond

Its estimated that almost one in five of all cathedrals

built in the middle ages suffered

catastrophic damage or collapse.

- We live in a day and age where we have

the mathematical capabilities

and the computational capabilities to work out stress,

how far we can push materials structurally.

They didn't have that technology available to them.

- Compression, the downward force of a building's own weight

was often the culprit in the collapse of cathedrals.

The stone structure too heavy for slender columns.

Modern demolition experts have learned that

when buildings have to come down,

they often simply need to take out the pillars

and compression will do the rest.

[music]

Despite the many collapses, dozens of Gothic cathedrals

across Europe still stand today, iconic buildings .

And iconic buildings often bear witness

to the great moments of history.

Notre Dame has seen coronations, canonizations,

funeral masses and notable marriages.

It's hosted important visitors.

Some more welcome than others.

Sometimes being an icon can draw unwelcome attention.

In the French revolution in 1789, Notre Dame was attacked

as a symbol of the old regime.

Statues were destroyed.

Windows smashed and the mighty bronze bells melted

down to make canon but the cathedral stood firm

throughout the turbulence centuries until 2019.

Notre Dame was undergoing major renovations when

around 6:00 PM on April 15th, it's fire alarm sounded.

Guards investigated but could find no flames.

It turned out they'd searched the wrong area.

By the time they realized their mistake, it was too late.

The fire raged for 15 hours.

Lead from the roof melted

and ran down the building like water.

Flames soared hundreds of feet into the sky.

At around 8:00 PM, the Spire collapsed.

400 firefighters tackled the blaze

but structural engineering experts advised

against fighting the flames from the air.

The weight to falling water would cause collapse.

Instead they risked their lives to tackle the fire from

within the structure.

Raving ferocious temperatures

and the risk of falling masonry.

The fire burned all night.

By 7:00 AM, the danger was over.

Firefighters put out the last embers.

The roof and vault were gone and the interior

left blackened and ruined.

- The world really did weep on April 15, 2019

when Notre Dame did go up in flames

It had been such an icon of Paris and France,

but also of everything

that had occurred from the Gothic era.

- But it's Testament to Notre Dame's

original brilliant engineers

that the walls towers largely survived.

Even the 13th century rose windows stood firm.

Notre Dame will rise again

And Gothic engineering isn't over.

There have been revivals and in Spain

one spectacular modern flourish.

The Sagrada Familia in Barcelona is taking Gothic

in a totally new direction.

It's architect Antoni Gaudi took on the project in 1883

and decided to attempt something far more intriguing

than just another Gothic structure.

Gaudi was already renowned for stunning homes

built in an Art Nouveau style, Casa Calvet

and the Guüell Palace

But his defining project aimed to surpass even

the greatest feats of Gothic engineering.

Could it be done?

Just as eight centuries before,

new engineering would have to provide solutions.

- The Sagrada Familia, it's evolving as it's being built.

And so it shows the ongoing story of cathedral building

- To complicate things further,

Gaudi wanted to build a structure with no right angles

or even any straight lines.

This truly was something totally new.

- It is the vision of a visionary architect

who is seeking to express not just architectural practices

but also expressing his own very personal devotion

to particular theological ideas.

- Gaudi liked to use scale models in his work.

And for the Sagrada Familia built a series

of upside down hanging models.

- Gaudi was trying to make a structure

like Gothic Cathedral

essentially a compression only structure.

- The models allowed him to analyze how forces would move

through his building

enabling him to create a compression only structure

where the force has traveled downwards not sideways.

And so dispensing with the need for buttressing.

Unfortunately, many of Gaudi's models were destroyed

by anarchists in the Spanish civil war.

So engineers have had to use modern computerized

techniques to achieve Gaudi's vision.

The resulting engineering solutions are inspired.

The main piers of the church lean outwards

to help balance the structure.

And thanks to the innovative forms Gaudi developed,

holes are punched in the volts

allowing light into the church from above

something Gothic cathedral builders

of the past could never have achieved.

Ingenious double twist columns enabled this structure

to soar higher than any other religious building

in year-round. over 550 feet.

Gaudi died in 1926 before his cathedral was completed.

Work continues to this day.

The cathedral is proof that engineers

can take the Gothic project further.

- It's perfectly possible to build Gothic cathedrals

that are bigger than the ones that were done at the time.

Be very expensive but yeah we know

we could certainly go bigger.

So far it's taken over 130 years

to build the Sagrada Familia

and nobody knows exactly when the final stone

will be set in place.

Perhaps further Gothic cathedrals will one day

follow this one

potentially reaching even higher than Gaudi's masterpiece.

The human race has created sacred spaces

since the dawn of history,

constructing devotional buildings of beauty and serenity

to honor the gods.

And the great Gothic cathedrals are houses of light

soaring heavenward, pinnacles of achievement,

still awe inspiring today, monuments to the skills

and imagination of ancient engineers.

[exciting music]