Original subtitles

[Narrator] These are the engineering wonders of Spain.

Their secrets revealed in a way never seen before.

For centuries, visionaries shaped this land

with lavish palaces, grand stadiums,

and cathedrals of breathtaking scale.

Today, Spanish engineers build on this history,

blending tradition with pioneering stretches

and cutting-edge machines for the modern world.

In this series, we reveal the secrets of the engineering

that built Europe's great nations,

the wonders that shape its cities,

landscapes, and history.

We reveal the astonishing innovations

and surprising connections

that help to forge this mighty continent.

♪ ♪

♪ ♪

Spain lies on the southwestern frontier of Europe.

This arid mountainous nation is a bridge

between North Africa and southern Europe.

For centuries, Spain has been shaped

by different civilizations that have crossed into this land,

including Romans, Muslims, and Christians.

Spain's engineers have drawn on this history

to meet the needs of the future by reshaping buildings

like Cordoba's former mosque

converted into a Catholic cathedral.

And landscapes, like in Elche, where Muslim engineers

turned a Roman date plantation into a flourishing oasis.

♪ ♪

Throughout the ages, Spanish engineers have pioneered

the construction of some of Europe's

most visionary public spaces.

Spain has a long history of constructing

religious buildings of astonishing scale.

In Seville, the Santa Maria de la Sede

is the largest Gothic cathedral in the world.

In Barcelona, engineers are taking cathedral construction

to new heights, completing a masterpiece

that's over a century in the making.

♪ ♪

This is La Sagrada Família,

Barcelona's famous unfinished cathedral.

It's an engineering wonder that's been under construction

since the late 19th century.

The building is made from over 200,000 tons

of carved stone blocks.

Each facade is engineered to depict

a different chapter of Jesus' life.

The walls of the 18 towers are dotted

with hundreds of intricate windows to cut weight

and allow more light to flow through the atrium.

Once complete, it will be the tallest religious building

in the world.

This revolutionary cathedral was the brainchild

of the maverick Spanish designer, Antoni Gaudí.

Now, over 140 years since they started work,

it's finally nearing completion,

led by architects like Xisco Llabres.

[speaking Spanish]

[Xisco Llabrés, translated] He had such a big vision

that he knew he wouldn't be able to finish it himself.

So Gaudí laid the groundwork for those who would come after him,

for his successors.

[Narrator] Work on the building started in 1882,

but progress stalled in the 20th century

with Gaudí's sudden death in 1926.

And after anarchists set fire to his early drawings

and models during the Spanish Civil War.

By 2014, only 60% of the building had been finished.

But in the last decade, modern engineering breakthroughs

have dramatically sped up the construction

of Gaudí's intricate designs.

[Xisco] There's a lot of experimentation

with new and innovative techniques.

Things we started testing here 10 years ago,

like fiber-reinforced concrete.

Now it's become a standard material in construction.

[Narrator] Fiber-reinforced concrete is used to strengthen

the stone panels in the building

of the spire of Jesus Christ.

It's the tallest and heaviest of all the towers

and the most challenging to construct.

To build a spire that the old foundations can carry,

the team must use slender sandstone.

But in high winds, the spire could bend and possibly break.

So they give the spire of Jesus Christ a backbone

of concrete and steel.

And to strengthen the stone panels,

they tension them with steel wires

and slot them into the steel scaffold.

This way, the majestic spire will fulfill Gaudí's vision,

rising almost 200 meters into the air,

safe from even gale force winds.

Carefully designed connections ensure that when workers

lower the panels into place,

they lock together without the need for on-site adjustment.

Sensors record the tension and movement of the steel scaffold

to measure how the load is balanced

between the stone blocks.

This guarantees each one is fitted correctly.

Inside the church,

the branching, tree-like columns gently tilt.

These angles give the columns enough strength to hold up

the ceiling without the need for external buttresses.

The central columns are the thickest

and will support the incredible Jesus tower

when it is finished.

♪ ♪

La Sagrada Família is set to be completed

exactly 100 years after the death of Gaudí,

and will be a fitting tribute to his legacy.

[Xisco] I never imagined I'd have the chance to work on

the Sagrada Família, let alone help finish it.

It's spectacular.

♪ ♪

♪ ♪

[Narrator] Spain is one of Europe's hottest countries.

For centuries, the people here have engineered clever ways

to seek shade from the sun.

At the Alhambra in Granada,

deep courtyards with water features and lattice screens

create cool, shaded spaces.

In Andalusia, entire villages known as Pueblos Blancos

are painted white to reflect the heat.

In Seville, this age-old battle for shade

has taken on an innovative twist.

♪ ♪

♪ ♪

In the historic old quarter

sits a record-breaking monument to timber engineering.

This is the Setas de Sevilla,

known locally as the mushrooms.

Six large wooden honeycomb parasols

tower over Plaza de Encarnación,

providing shade to shops, bars and restaurants beneath.

The structure is made from over 3,500 pieces of pine.

At over 150 meters long, 70 meters wide,

and 28 meters high, it is thought to be

the largest free-standing wooden structure in the world.

It's the job of José Pedro Pulido to ensure

this masterpiece of wooden engineering stays standing.

[José Pedro Pulido, translated] We're always keeping an eye

on this structure, making sure it's in top condition

and everything stays in the best shape.

If anything important comes up,

we're ready to act fast and fix it right away.

[Narrator] Construction of the mushrooms started in 2006.

Designers opted to use a composite material

made from thin layers of wood glued together.

This makes the structural elements stronger

and lighter than solid timber.

Over 16 million nuts and bolts join the beams together.

A metal viewing platform and walkway snakes across the top,

providing 360-degree views of the skyline.

A weatherproof resin coats the surface of the structure,

and it's topped up every decade.

But even this protective layer has its limits.

In Spain's harsh climate, with cold winter nights

and summer days exceeding 40 degrees,

the wood expands and contracts, putting strain on each joint.

[speaking Spanish]

[José] We monitor humidity levels at around 20 points

across the structure, using metal plates and steel screws

inserted into the wood to take readings.

[Narrator] Throughout the year, José's team survey

the entire structure to examine whether joints have shifted

and to tighten any loose bolts.

For more than two centuries,

the Plaza de Encarnación had been a thriving market

in the heart of Seville's old town.

But by the 1970s, the area was in decline.

That all changed when Roman ruins were discovered

beneath the site, sparking plans to protect the history

and revive the space.

The result was Setas de Sevilla,

a bold sculptural landmark that shields the square

from the scorching sun and brings new life to old Seville.

The mushrooms are more than just a showcase

for spectacular timber engineering.

Electrical engineering is on full display here, too.

[Narrator] Hidden within the beams of Setas de Sevilla

are sensors hooked up to LEDs and speakers

that respond directly to changes in the environment,

including wind speed, air temperature,

and crowd movement.

[Pedro Parrilla Calle] From sunset to midnight,

we have every day a different show created by the software,

a new immersive experience for the visitor.

[Narrator] As night falls, inputs from the web of sensors

trigger an ever-changing light show across the surface.

The audio visual spectacle, known as Aurora,

transforms the structure

into a glowing landmark for the public.

This audacious piece of civil engineering has achieved

its goal of reviving the old quarter

by creating an icon that both protects people from the sun

and attracts art lovers and business,

which, in turn, boosts the economy.

♪ ♪

Spain's legacy of building astonishing public spaces

is not just a modern phenomenon.

It goes back millennia.

On the shores of the Mediterranean,

Tarragona's Roman amphitheater once housed 1,400 spectators

to watch gladiatorial combat.

While in the ancient town of Mérida,

one Roman site is remarkably still in use

2,000 years after it was first built.

♪ ♪

Mérida is one of the world's best preserved Roman cities.

The jewel in its crown

is the oldest working theater in the world.

♪ ♪

The stage is 60 meters long

and has a backdrop that rises almost 20 meters into the air.

Decorative features, including columns, statues and cornices

were made of beautiful marble

imported from across the empire.

But for the main structure and foundations,

the Romans used durable local granite.

Added strength came from extensive use of concrete.

Unlike modern concrete,

the Roman mix was made of lime, water, and a secret ingredient:

a volcanic ash called pozzolan.

This made it extremely strong and long-lasting.

The result is a 2,000-year-old theater,

so tough, it's still in use today.

At its peak, the theater could hold up to 6,000 spectators,

and modern-day crowds still pack its marble terraces

for music, film, and theater performances.

Annual inspections ensure it remains safe

and well preserved.

Conservationist Maria Paz Perez is leading the work.

[speaking Spanish]

[Maria Paz Pérez, translated] The problems we see

are deterioration caused by the weather.

Exposure to the sun and rain,

because they're open to the elements.

These buildings are 2,000 years old,

and we also have to work around the visitors.

[Narrator] The cornices are made from white marble,

which is strong but porous.

This makes them vulnerable to weathering.

Conservators must protect their horizontal surfaces

with a layer of render.

As they carry out their inspections,

Maria's team find an area

where this protection is flaking away.

It's not just the weather this theater has to contend with.

The damage can also be accelerated

by modern-day sound systems.

Vibrations caused by loudspeakers

during iconic performances

can cause the crumbling marble to collapse.

To combat the problem, the conservation team

have introduced strict guidelines.

[Maria] We have already established the parameters

that cannot be exceeded.

So all of the companies know they can't go beyond

that set level of decibels

so that it doesn't affect the monument.

[Narrator] To repair the flaking stonework,

the team uses a special render

that is made to an ancient recipe of lime, sand

and powdered marble.

[Maria] This mortar is applied to protect the upper part

of the cornices, because everything is out in the open.

It's the only way to protect it, since the monument has no roof.

[Narrator] Now it's time for the team to perform

their vital intervention.

[Narrator] The restoration team applies the layer of render.

Once it dries and weathers,

it will blend in seamlessly with the original marble,

protecting the cornices from the ravages of the elements

and musical vibrations.

[Maria] I feel that doing this work contributes

to future generations being able to enjoy,

contemplate, and study this heritage.

[Narrator] As long as engineers continue this painstaking work,

Mérida's masterpiece of Roman engineering

will host performances for another two millennia.

♪ ♪

♪ ♪

Spanish engineers have not only pioneered the creation

of extraordinary public spaces, they have also trailblazed

the construction of spectacular architectural wonders.

♪ ♪

Across Spain, engineering marvels are transforming

the country's traditional landscapes.

Valencia's Turia River was diverted to prevent flooding.

The dry riverbed is now a vast urban park.

In Bilbao, the Guggenheim Museum

helped to turn the city's industrial dockland

into a world famous cultural hub.

In Rioja, the country's iconic wine region,

architects have revitalized the area's oldest vineyard

with a modern engineering superstructure.

♪ ♪

♪ ♪

This extraordinary vision is the Hotel Marqués de Riscal.

It was designed by Frank Gehry,

who also created the Guggenheim in Bilbao.

The hotel attracts over 100,000 annual visitors

to gaze at its stunningly engineered curves,

bringing economic benefits to this quiet corner of Spain.

Its roof is made up of approximately

3,400 square meters of titanium.

Titanium makes a good roofing material.

It is strong, light, and very resistant to corrosion,

but it can also be treated to produce

a surprising range of bright colors.

Gehry's vision was to use engineering principles

to create a modern work of art,

set within the region's oldest vineyard.

It's a venue maintained by hotel manager Stefan Friedl.

[Stefan Friedl] The idea was to have a building

that has no weight and it's floating

like the skirts of dancing Spanish girls flying in the air.

[Narrator] The different colors of the roof

at a final level of symbolism, representing a bottle of wine.

Red for the wine itself, silver for the foil

and gold for the mesh,

which covers each bottle produced here.

The project cost a total of 60 million euros.

♪ ♪

Just building the twisted steel backbone

for the signature canopies took almost three years.

And to fit the thousands of titanium panels,

the workers had to mount every single one of them by hand,

like a giant 3D jigsaw puzzle.

The twisted, overlapping roof may look spectacular,

but it makes cleaning the exterior a challenge.

Scaffolding and ladders risk damaging the titanium ribbons.

So Stefan works with a company that has developed

an ingenious engineering solution:

a drone equipped with a high-pressure water jet.

[Josele Bernabé] That's our main drone unit.

It's the most powerful drone,

which is able to be used legally in urban areas.

[Narrator] The drone has to be as powerful as possible

to compensate for the force of the water,

which constantly pushes it away from the surface,

creating unpredictable air turbulence.

[Josele] Sometimes we have some kind of shaking mass of air

affecting the drone.

So we need to be always ready

for any kind of strange reaction that the drone has.

♪ ♪

[Narrator] To make cleaning the building even more difficult,

the combination of metals in the roof actually generates

its own electromagnetic field,

which disrupts the drone's auto-navigation systems.

[Josele] All this structure affects the GPS signal

from the drone, affects the compass from the drone.

So we are flying almost in manual.

[Narrator] It takes two days to restore the building

to its pristine best.

[Stefan] It's just an amazing view,

which doesn't fail to give a warm feeling around my heart

every morning I come to work.

[Narrator] This innovative technology promises to preserve

architectural masterpieces like Hotel Marqués de Riscal

for years to come.

♪ ♪

Spain has a long history of transforming

its most treasured landmarks.

The Alcázar of Toledo was a palace built by Romans,

then became an Islamic fortress, and later expanded

during the Christian era to become a royal residence.

♪ ♪

In Madrid, cutting-edge architects are giving

a facelift to an engineering wonder of the city's skyline.

[Narrator] The 117-meter-high Columbus Towers

loom over the heart of Spain's capital city.

And they have been an icon of Madrid's skyline

for over 50 years.

Their most striking feature is that this enormous structure

appears to be supported

by just the thinnest of concrete stalks.

The building's gleaming glass exterior is brand new,

but their gravity-defying internal structure

dates back to the 1960s.

And it's an example

of one of the world's weirdest architectural ideas.

Hidden beneath the gleaming glass

are two slender concrete cores

that the whole building rests on.

Two extremely sturdy slabs sit at the top.

Each serves as an anchor point

for the heavy duty steel cables.

Wrapped in concrete,

they support the concrete floors of the building,

suspending them like the rungs of a rope ladder.

It's an ingenious design that almost makes it look like

the Columbus Towers are floating in midair.

♪ ♪

♪ ♪

Architect Luis Vidal is the mastermind

behind the towers' most recent transformation.

His renovation adds a four-story glass box

to the original towers' design,

a sleek new glass bridge to connect the two towers,

and modern reinforcements to the aging cable stays

that hold the building together.

After four years of construction,

Luis and his team are performing a final inspection

before handing the building over to its new owners.

[Luis Vidal] We want to make sure that everything

is looking as we designed

and make sure that everything is working as envisioned.

[Narrator] While Luis examines the interior of the building,

his colleague Manuel inspects the exterior works.

[Luis] We want to go down to level 24

so we can see the brackets and how the new cables are working.

[Manuel] Understood.

[Narrator] Manuel reaches the point

where the long, steel stay cables start their journey

down the outside of the building.

The pale gray columns house the original steel cables

from 1967, but each column is now flanked

by two sleeker, black additions.

[Manuel] Everything's looking pretty solid, to be honest.

Looks fantastic.

[Narrator] The original cables still help support

the building's weight.

But the new 21st century cables

add extra strength and resilience.

The team still has to inspect the improbable glass box

perched on the top of the two towers.

♪ ♪

Luis' bold idea to transform the towers

was to create new office space on top of the structure.

Whilst the building below is a wonder of 1960s engineering,

this new addition is a marvel of 21st century design.

Luis' daring engineering innovation was to use glass

as a main structural element,

eliminating the need for internal pillars.

[Luis] What's really interesting about the structure

is that all the glass is curved.

If you get a single piece of glass

and you place it vertical,

it falls.

But if you curve it, it's free-standing.

This is the principle of what we have designed here.

We don't need any mullions. We don't need any columns.

We don't need anything.

[Narrator] With the inspection complete,

the building is ready to be handed over.

This engineering marvel will remain a striking feature

of Madrid's skyline for years to come.

♪ ♪

♪ ♪

Sport has been a pillar of Spanish culture

throughout history, and inspired engineers

to construct stadiums of remarkable scale.

In Madrid, Las Ventas, Spain's largest bullfighting ring,

has drawn crowds for nearly a century.

While in Barcelona, the 1920s-built Estadi Olímpic

was reborn for the 1992 Summer Olympics.

In the city's Les Corts district,

engineers are building on the legacy

of one of football's most iconic stadiums.

[Narrator] This busy construction site

is giving Barcelona Football Club's stadium

the ultimate facelift.

Once finished, this massive redevelopment

will raise the capacity to 105,000 seats,

making it the largest football club stadium on the planet.

This unique transformation is

an extraordinary engineering challenge.

The new stadium is being built without destroying

the club's original and much-loved ground-level stands

from the 1950s.

Overseeing this complex process

is director of operations Joan Sentelles.

[speaking Spanish]

[Joan Sentelles, translated] No Barcelona fan could ever imagine

the stadium being somewhere other than in Les Corts.

This is our home.

This is where our heart is.

And this is where Barcelona Football Club stadium

should be.

[Narrator] The first step was to reveal the 1950s architecture

by removing the 1980s extension that sits around it.

Specialized machines resembling mechanical dinosaurs

carefully nibbled away the later additions,

leaving the original core untouched.

♪ ♪

Next, engineers built a free-standing ring of steel

around the old stadium to carry the weight

of the new development.

This avoids any unnecessary strain

on the stadium's original 75-year-old foundations.

The new third tier will hold 30,000 spectators.

A lightweight roof will cover every seat,

sheltering fans from the blazing Barcelona sun.

And 18,000 square meters of solar panels

will help make the stadium both sustainable and spectacular.

♪ ♪

The new cleverly engineered third tier is designed

as a cantilever, so it will appear to float

above the old stadium.

The external ring of steel also bears the weight of the roof.

The stadium's new framework is inspired

by 1930s New York skyscrapers.

To erect it, workers use prefabricated steel beams,

manufactured to precise tolerances

that simply bolt together.

A layer of concrete then adds extra strength and stability.

This rapid assembly technique allows the 3,500-strong team

to construct around 600 tons of steel in a week.

[Joan] To give you an idea, the Eiffel Tower weighs 7,000 tons.

In two and a half months, we built an Eiffel Tower.

[Narrator] Remarkably, much of the raw building materials

have been recycled from the demolition of the old stands.

97% of the old steel will be reused in the new construction,

lowering the carbon footprint of the new design,

as well as incorporating elements of its past.

♪ ♪

With the finish line in sight and hopes of welcoming fans

even before construction is fully complete,

Barcelona's new stadium is set to captivate audiences

across Europe and beyond.

♪ ♪

Spanish engineers have not only constructed

epic architectural wonders, but also spearheaded the invention

of cutting-edge machines.

♪ ♪

♪ ♪

For centuries, the nation's innovators have found

groundbreaking ways to traverse Spain's rugged landscape.

In 1907, engineers constructed Spain's first-ever cable car

on Mount Ulia near San Sebastián,

while Spanish engineer Juan de la Cierva

built the world's first autogyro,

the precursor to the helicopter.

In the Basque region, engineers are using innovative machines

to create an ambitious new high-speed rail line,

linking Vitoria, Bilbao, and San Sebastián

through the Pyrenees mountains.

♪ ♪

The Basque Country, located in the western Pyrenees,

has rugged, mountainous terrain.

This creates a major challenge for the engineers

building the new railway here.

The tracks' viaducts need to be extremely tall

to span vast chasms.

It's not practical to construct them

using traditional techniques, with cranes hauling

their concrete sections into place block by block.

So engineers use remarkable machines

that cast the bridge sections in situ from liquid concrete

poured up to 100 meters in the air.

♪ ♪

Javier Selvas Arsuaga is in charge of building

a key section of this high-speed line,

which includes the Arrazola viaduct.

It's a 1,755-meter-long overpass

connecting the towns of Atxondo and Abadino.

[Javier Selvas Arsuaga] I have worked on a lot

of very important projects,

but this project is very interesting.

It is the longest viaduct on the entire line.

♪ ♪

[Narrator] The innovative machines at the heart

of the project are giant frames,

known as movable scaffolding systems

that balance on top of the bridge columns.

Their insides form a mold for the team

to pour in liquid concrete.

Once it's set, the machine opens

to reveal the new bridge section.

Then it moves along, ready for the next pour.

Today is the big day to unveil the latest bridge section.

But before they can open the mold,

Javier must wait for the concrete to fully set.

[Narrator] In the foothills of the Pyrenees,

the crawling, yellow, movable scaffolding system

is part of an army of machines,

building viaducts across the landscape.

This red machine in a nearby valley

is preparing for its next pour of concrete.

First, it contracts to create a mold

for a 66-meter section of the viaduct.

Then engineers carefully position a dense network

of steel rods inside the mold

to reinforce the strength of the viaduct.

♪ ♪

Next, they pour in the concrete to form the base, sides,

and finally the deck of this massive structure.

♪ ♪

At the Arrazola viaduct, the concrete is finally set,

and it's time to open the machine.

Powerful hydraulic pistons swing open the scaffold.

Javier is now able to inspect the new section.

[Javier] We want to make sure there are no fissures

or large cracks before we continue to the next section.

[Narrator] The viaduct's undercarriage is too high

to examine from the ground,

so the team use a drone to get a better view.

♪ ♪

[Javier] I am happy because it turned out well.

[Narrator] Over the coming weeks,

the Arrazola viaduct will take shape

and eventually join the largest

high-speed rail network in Europe,

with the lowest average construction cost.

These mega machines are a game changer,

speeding up construction and allowing engineers

to lay over 50 meters of viaduct a week.

Each completed section of high-speed rail track

brings Spain closer together, strengthening bonds

between the regions, as well as neighboring countries,

providing a major boost to the nation's economy.

♪ ♪

♪ ♪

Spain's arid climate has forced the nation's engineers

to innovate to sustain its agriculture.

In Segovia, this nearly 2,000-year-old aqueduct

once channeled water to irrigate the city's crops.

In Alcalá del Río, just outside Seville,

an innovative new machine is revitalizing

one of Spain's oldest industries.

♪ ♪

This monster contraption is a multi-harvester,

designed for use in high-density olive groves

and nut tree orchards.

But on this experimental research farm,

they are trialing it to harvest oranges.

Local farmers are here

to see this revolutionary technology in action.

The trial is part of a growing movement

to harness pioneering technology

to revolutionize Spanish farming.

Francisco Arenas is the farm's director

and a leading researcher in citrus cultivation.

[Francisco Arenas, translated] Currently, the problems that

farmers face in citrus cultivation

are the shortage of available labor

and the increase in harvesting costs.

[Narrator] For generations, workers have picked oranges

by hand, a labor intensive process

that can take weeks to complete.

And oranges are grown on large trees, seven meters tall,

which makes harvesting even more difficult and dangerous.

[Francisco] We're always looking for the possibility

of harvesting in a more comfortable way

and avoiding the use of ladders.

[Narrator] Francisco studied the mechanization of other crops

to work out if orange farmers could adapt

and use this new generation of machines.

His solution was to change the way orange trees are nurtured

to make them more suitable for machine harvesting.

Francisco's team grow their oranges on low bushes

instead of tall trees,

pruning the branches to keep the rows compact.

The new trees were planted three years ago.

They are now mature enough for Francisco to experiment

with a new machine to harvest the oranges.

[speaking Spanish]

[Carlos Lucas Sans, translated] This machine rides over the hedge.

It's like a tunnel that receives the hedge

and squeezes it into the shaking area.

[Narrator] The machine uses an ingenious system

called shaking dynamic control to pick the fruit.

It deploys 36 curved plastic bars that oscillate

at a precise frequency to carefully loosen the oranges.

♪ ♪

[Francisco] The vibration frequency should not be

too high to avoid a lot of damage to the tree,

but high enough to release the maximum percentage of fruit.

[Narrator] Underneath the shakers,

a belt of plastic petals gently closes

around the trunk of the tree

to form a basket which catches the oranges.

This belt moves at exactly the same speed as the harvester,

but in the opposite direction.

This means the basket remains static around the tree

to minimize damage.

♪ ♪

Conveyor belts move the oranges upwards.

Powerful blowers remove the twigs and leaves

as they fall into the collection hoppers.

The machine gathers 30 tons of oranges in just two hours,

a job that would take 15 workers two whole days

to achieve by hand.

[Carlos] In the end, simply one operator is able to operate it

and work six to 10 hectares during the day by himself.

[Narrator] By adapting traditional practices

to use this innovative new machine,

orange farmers can take a major step forward

to ensure one of Spain's historic industries thrives

for generations to come.

♪ ♪

♪ ♪

Spain is a nation shaped by millennia of cultural influence

and architectural brilliance.

Today, its engineers draw on that rich heritage

to reinvent historic spaces,

crafting a legacy for the centuries ahead.