All language subtitles for Ancient.Engineering.S01E05.Secrets.Of.Notre.Dame.1080p.AMZN.WEB-DL.DDP2.0.H.264-NPMS_track3_[eng]

- [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]