Original subtitles

[narrator] In Greece...

an elite team of engineers is embarking on

an extraordinary endeavor.

Up, up!

They're attempting to build a state-of-the-art skyscraper

in one of the world's oldest cities.

Working along the coast, the team must battle

unstable ground...

We always say, whenever you excavate in

the soil, you have no idea what you're gonna find.

...the threat of earthquakes...

Lots of buildings were damaged and a few of them

even collapsed.

...and dizzying heights...

The higher we go, the riskier it gets.

...to build this one-of-a-kind structure that will transform

the skyline of Athens forever.

This incredible tower ranks in a league of ambitious new

engineering wonders that are bigger, faster, taller,

and more advanced than anything ever constructed before.

This is the inside story of the extraordinary challenge of

building these giants.

[explosion blasts]

Athens, Greece.

A city where modern apartments sit alongside some of

the world's most famous ancient structures.

This city's three million inhabitants live in one of

the most densely populated areas in Europe.

Athens desperately needs space to grow.

The city planners' bold solution is to redevelop

the site of Athens former Ellinikon International Airport.

Covering over 66.5 million square feet

beside the Mediterranean,

it is one of the world's largest

urban regeneration projects.

The plan is to transform the site into

a new coastal district...

with premium homes, luxury hotels, retail areas,

and a huge park.

Antoinette Nassopoulos-Erickson leads the design of

the new development.

[Antoinette] The Ellinikon master plan is really defining a sort of

a new way of living in Athens, I believe.

The concept, which is built up around this park

as a central focus, and then several

different neighborhoods that sit around

the edge of the park.

Once complete,

this smart city will be super efficient and ultra-connected.

It will feature public Wi-Fi and shared e-bikes,

alongside an intelligent waste management system

that notifies workers when it needs to be emptied.

The centerpiece of the plan is the Riviera Tower.

The Riviera Tower is to be the icon and a symbolic element

for the whole development.

This green city, this new way of living, which was

this connection between nature and lifestyle,

all of those principles came in to shape

and form the idea of this tower.

At over 650 feet tall, Riviera Tower will be

Greece's first true skyscraper,

housing 170 luxury apartments.

At its center will be 47 open terraces.

All 23 of the sea-view terraces

will have their own infinity pools,

where residents can soak up the glorious

Mediterranean climate.

29,000 aluminum composite panels

and 1,600 panes of special wind-resistant glass

will cover the exterior of the building.

To help it blend in with the surrounding parkland,

the team will embed 38,000 plants across the tower,

including the world's tallest continuous green wall.

Constructing this tower within the projected

four-year time limit won't be easy.

It falls to development director George Giannakopoulos

to hit the deadline.

The project requires three million

cubic feet of concrete.

Summer temperatures in Athens can reach

nearly 100 degrees Fahrenheit.

Temperatures this high can

cause concrete to crack as it dries.

And powerful storms batter this coastline.

Winds above 30 miles an hour will shut down the build.

[George] It is a challenging one.

There's a whole team of people which we need to work around

the clock to make this project a reality.

And building tall in this part

of the Mediterranean presents a big risk.

On average, Greece experiences 25,000 earthquakes per year.

In September 1999, an earthquake registering 5.9

on the Richter scale struck Athens.

More than 100 buildings collapsed,

and 143 people lost their lives.

Engineer Alfredo Gonzalez must design a foundation for

the tower that is strong enough to withstand

a powerful earthquake.

[Alfredo] It's a big challenge for us.

Greece is in the confluence of four tectonic plates,

and the foundation is required to stay solid and as undamaged

as possible because they hold the building in one place,

they anchor it to the ground, and they prevent damage from

spreading beyond the structure.

This is how Alfredo's solution works...

First, the team drills 111 five-foot-wide holes to reach

the bedrock nearly 165 feet beneath the surface,

followed by 205 shallower holes around the outside.

Workers drop steel reinforcement cages

into the holes.

Then pour concrete over them to

create super-strong pile foundations.

Next, they excavate a 16-foot pit around the top of

the deep piles,

and fill it with steel reinforcement.

The last stage is to pour more than

18 and a half thousand tons of concrete to

make the main raft foundation for the tower.

It's the responsibility of Konstantinos Terzis

to make sure the team sinks the foundations correctly.

Nobody has done this in Greece before.

We are the first.

The foundations are actually the most important aspect

of the high-rise building.

The foundation work begins in 2022.

The team uses a huge piling rig to drill 111 holes,

165 feet into the ground.

This is the first time anyone has drilled this deep for

a residential project in Greece.

[Konstantinos] As we always say, whenever you excavate in

the soil you have no idea what you're going to find.

Drilling this far down creates a big challenge for the team.

The pressure on the hole increases the deeper it gets.

The hole could collapse.

The team's solution is to pump

a material called bentonite into the shaft.

Bentonite is a clay-based slurry.

As it fills the shaft, it closes the gaps in

the exposed ground and forms a thin layer that

seals the walls.

The mixture prevents the hole from collapsing.

Now, the team must install the cylindrical lattice

of steel to reinforce it.

The site's coastal location

presents a big danger to the steel's health.

[Konstantinos] We are so close to the sea.

Groundwater is constantly penetrating in the site.

In the long term, when seawater comes in contact with

the steel, there's corrosion.

Corrosion is basically the cancer of the steel.

So, this means that it's not gonna carry the loads

as it should, and...that's not good.

To prevent corrosion, no part of the steel cage can contact

the wall of the shaft when it's in its final position.

Workers carefully lower the cage into the hole.

They attach concrete spacers to

keep the steel clear of the shaft wall.

Inch by inch, the cage descends into its final position.

Next, the team fills the hole with concrete.

It takes just six hours to set into a super-strong pile that

helps to pin the tower's foundation to the bedrock.

Over the next seven months,

the team sinks the 111 long piles

and the 205 short piles into the ground.

The next challenge is to create

a huge foundation slab for the tower's base.

In Athens...

a team of engineers is constructing a brand-new

earthquake-proof skyscraper.

The 50-floor Riviera Tower will need rock-solid foundations to

help it withstand powerful quakes.

The engineers design an over-21,000-square-foot slab

for the tower to stand on.

Imagine two Olympic pools side by side, twice the depth of

an Olympic pool, so quite huge foundation structure.

Constructing this massive foundation slab presents

engineers with a major challenge.

They must ensure the slab connects with the piles to form

a single, unified foundation structure.

[Alfredo] It's a very important function.

It's used to hold everything together and avoid

relative displacements within the structure.

Workers must dig down to reveal the top of the piles.

They then need to build the steel reinforcement cage

around the piles...

before pouring over 18,500 tons of concrete for the slab.

Workers excavate a 16-and-a-half-foot pit to

expose the piles.

Next, they use a machine called a pile cropper

to slice the top off each one.

This reveals the rebar inside the pile to ensure

a strong bond with the concrete that the team will pour

into the pit.

The team assembles the steel reinforcement.

Workers fabricate a 158-foot by 158-foot steel cage

from 2,200 tons of steel rebar.

Now, it's time to pour the concrete.

The concrete pour of the foundation is very critical.

It's a very complex logistics operation because we're talking

about a very big quantity.

The team must lay down

247,000 cubic feet of concrete.

This will be the largest concrete pour ever attempted

in Greece, and they must complete it within 48 hours.

Weak points will form in the concrete if the team allows

one layer to cure before they pour the next.

So, they must pour continuously.

This operation, you have to get it right on the first go

because there's not going to be another chance.

So, we are hoping for the best

and we're planning for the worst.

The team builds huge concrete plants on site to supply

a fleet of mixer trucks.

[Konstantinos] We have to pour the concrete as quickly as possible so

the truck goes away, next truck goes in.

We are using three batching plants as well as

one backup plant, just in case.

So there's a Plan A and there's a Plan B as well.

The mega concrete pour begins.

More than 120 concrete mixer trucks shuttle nonstop

between the plants and the site.

The team uses eight pumps with extendable arms to pour

the concrete into the huge steel frame.

♪♪

Work continues into the night to keep the pour going.

The team smooths the surface of the concrete to ensure that

it's completely flat before the next layer goes on top.

After 40 hours, the pour is complete

and the huge foundation block is finished.

[Konstantinos] The entire team should be very proud,

from every worker to any traffic master

who took participate in the operation,

to the people in the batching plants working day and night.

It was a very fulfilling moment.

With the foundation in place,

the team can now build above ground

and start the walls and floors of the tallest tower in Greece.

The construction of the tower is what follows next.

Now, the hard part begins.

Engineers in Athens are building

Greece's tallest building.

The architects of the Riviera Tower envision

a skyscraper that offers its residents the perfect

Mediterranean lifestyle.

Nicola Scaranaro is part of the team tasked with crafting

this revolutionary structure.

[Nicola] We wanted to design a building

rooted in Athenian traditions and way of life.

Nicola and the team design the tower

with an outdoor terrace on every one of its 50 floors.

The temperature in Athens in the summer can reach

nearly 100 degrees Fahrenheit.

The team builds in an ingenious solution to keep

the terraces cool.

The central spine of the building is completely open

to let the sea breeze coming through, especially during

the mid-season in the summer, which will enhance the comfort.

But opening up the tower in this way creates

a big engineering challenge.

The concrete core of a traditional skyscraper is

the building's backbone that gives it most of its strength.

So the architects of the Riviera Tower must find

another way to keep it strong.

[Nicola] And so we thought of creating the split core

with this gap running through the middle.

This is how it works...

Engineers use a mold called jump form

to build two cores

with a gap in between.

They fill the mold with steel reinforcement and concrete to

cast a single floor.

Once the walls have cured,

hydraulic jacks lift the jump form to the next level,

where the casting process is repeated.

Three levels below the jump form, the team constructs

floor slabs around the core.

A hydraulic safety fence rises with the tower

to make each new floor safe.

Workers must repeat this process over and over again to

build a floor every six days

until both cores reach 50 stories high.

It takes the team six months to

build the lower levels of the tower.

The workers are now ready to install the jump form.

It's the responsibility of Jerome Mulot

to keep this part of the build on track.

♪♪

Floor by floor, the cores begin to rise.

The team must work quickly to stay on schedule,

but they can't afford to compromise on quality.

[Jerome] The cores are the backbone of a project.

They are the key structural element.

The quality of the construction

is paramount, so [indistinct] is sound and safe.

Riviera Tower is located within an active earthquake zone.

It must withstand quakes stronger than any recorded

in the region's history.

To make the tower strong enough,

workers use much more steel reinforcement

compared with a standard 50-story building.

There is much more steel than a similar project built in

a non-seismic area.

The steel rebar is so densely packed

that the gaps in between them are small.

The danger is that the liquid concrete can't get into

every gap and creates weak points within the cores.

To prevent this, the team uses a vibrating probe to agitate

the concrete and make sure that it trickles into

every part of the structure.

It takes the team nine months to build the first ten floors.

But as the tower rises,

the risks to the safety of workers on site increase.

Tools and materials dropped over the side of the tower

could be deadly to people on the ground.

Prince Chuksuobasi is responsible for safety on site.

[Prince] We have roughly about 1,200 workers,

so it presents indeed a lot of challenges.

Our biggest fear is objects falling.

The higher we go, the riskier it gets.

When an object fall from 10 meters to the ground,

the impact cannot be the same when an object drops

from 50 meters all the way down.

To eliminate the danger from falling objects,

the team surrounds the upper levels with a series of nets,

catch fans, and a mechanized safety fence.

[Prince] The safety fence is around the area where

the structural works are being done.

As the building progresses, the safety fence goes with

the progression of the tower.

[indistinct]

Today, workers are raising

a section of fence to the next floor.

They use two hydraulic jacks to make the lift.

Up, up.

Each jack pushes with a force of more than three tons.

They could damage the structure or injure a worker

if incorrectly installed.

The worker above controls the jacks...

while the team below monitors the progress.

The jack is too short to lift the fence in one go,

so it must cover the distance in stages.

Once it is pushed by one meter, we need to drop the jack

again to push it up by another meter.

♪♪

[indistinct]

[clanking]

After some fine-tuning, the fence section is in place.

Now that the area is protected, the team can move on to

constructing the floor slab for this level.

They will repeat this cycle

until the cores reach their full height.

The next challenge is to join the two cores together.

Engineers in Athens are racing to build

Greece's tallest building...

in an active earthquake zone.

The spine of the Riviera Tower is a pair of concrete cores

that will reach 656 feet in height.

The engineers must now join the two cores

to make a unified tower.

Architects design buildings in seismic zones to move when

an earthquake strikes.

This movement dissipates the huge energy of the quake

and prevents the structure from collapsing.

In a traditional skyscraper,

the single core moves with the rest of the building,

but a two-core structure like the Riviera Tower presents

engineers with a daunting challenge.

[Alfredo] When you have a structure that is supported by

two separate cores, the last thing you want

is them moving separately.

You can have things breaking up because they were not designed

to move enough, one side with respect to another.

Pools falling down, bridges between two towers also

breaking down and causing damage.

The two cores of the Riviera Tower must

move together in the same direction during an earthquake.

To do that, the tower's engineers build in

an ingenious feature.

First, they expose sets of up to 48 special connection points

embedded within the walls of the cores.

Next, workers build a cage of densely packed steel rebar

between pairs of connection points.

Then, they cast a nearly seven-foot deep

concrete beam over the cage.

They repeat this process for each level of the tower,

all the way to the top.

These coupling beams lock the two cores together,

and should ensure that they move

with perfect synchrony.

Stuart Ward is the project director overseeing

the construction of the tower.

The coupling beams are a very integral part of the design.

It's like -- basically like a ladder.

So, if you consider the towers as the two vertical elements of

the ladder, the rungs of the coupling beams,

they give it that extra stability.

An earthquake could strike Athens at any time.

It is critical that the cores are joined together from

the earliest stage of the build to prevent collapse.

Stuart must ensure that his team keeps pace with

the cores as they rise even higher.

The target is to be no more than seven floors behind.

There's a certain relationship between how high the core can

go before we need coupling beams in place.

First, the team drills away the surface of

the concrete cores to expose the metal connection points.

The coupling beam's huge size and weight prevents

Stuart's team from making them on the ground

and using a crane to lift them into position.

So workers must make each one in situ from up to

96 super-sized steel bars.

Workers screw the steel bars into the connection points to

anchor the cage.

♪♪

They cut, bend, and tie together lengths of

rebar to make the lattice work.

Next, they assemble a mold around it.

And the team gears up to pour in

more than 280 cubic feet of concrete.

It takes 28 days for it to cure and achieve full strength.

Now, this fresh coupling beam is ready for inspection.

Stuart checks the surface of the concrete for a defect

called honeycombing.

This occurs when the concrete cures with air pockets inside.

We need to make sure that there's not significant amounts

of honeycombing or for areas where the concrete wasn't

properly vibrated.

This particular one is pretty good concrete.

There's no issues with this. Very happy with this.

Now that the coupling beams are holding the cores together,

the team can start work on the terraces that make

this tower so distinctive.

In Athens, a team of engineers is building an ambitious

new skyscraper on the stunning Mediterranean coastline.

A key feature of the classic

Athenian apartment is its terrace.

The Greek lifestyle is always about being outdoors.

When you look at the sort of standard apartments in Athens,

those apartments have great terraces, balconies.

They became another room,

an extension of your living space.

Antoinette and her team translate this idea to

Riviera Tower.

They designed the skyscraper to have a giant terrace with

its own swimming pool on every second floor

to unlock stunning vistas.

The idea was to maximize the views.

There are terraces at the front and the back of the tower,

so some of the apartments are forward-facing to the sea,

others are facing to the mountain.

Building the terraces presents

the engineers with a big challenge.

The structures must have no load bearing columns to block

the spectacular views.

Each one must be a single giant slab of concrete that spans

the nearly 27-foot gap between the skyscraper's two towers.

Structurally, it's quite complicated

because it sits between the two towers.

The engineers' solution is to cast the terrace slabs on

a special metal frame called table formwork.

It attaches to super strong metal supports that reach

two stories high.

[Stuart] The terraces are every second level, which means

it's a double volume space.

So, it means that the height of

the formwork to construct that is much higher.

The table formwork is too heavy and bulky for

the construction team to carry to each floor.

So, one of the two special cranes on the top of the tower

must lift it to where it's needed.

These cranes are attached to the walls of the tower's cores.

Workers raise them up every time the cores grow in height.

The tower cranes that we have on the project, they're fairly

complex pieces of equipment.

The tower crane operators are highly skilled.

Today, crane operator Ghizlane Horn must lift

the table formwork for the 38th floor terrace.

Lifting anything from the ground up to crews

inside the tower presents a challenge.

Ghizlane has no line of sight to the floor

that she must deliver the formwork to.

She must rely on instructions from her co-workers on floor 36

to complete the task.

Ghizlane lifts the first section

of table formwork off the ground,

and up to the team inside the tower.

It weighs over two and a half tons

and will damage the concrete if it collides with the tower.

So Ghizlane's co-workers use ropes to help guide

the load to the drop point.

♪♪

[speaking foreign language]

Ghizlane drops off the formwork right on target.

Workers maneuver it into position.

[speaking foreign language]

It takes Ghizlane over three hours to deliver

all the parts of the formwork.

[speaking foreign language]

Now, the crew can build the terrace.

First, workers cut hundreds of lengths of steel reinforcement.

They lay these on top of the formwork to create

the skeleton of the giant slab.

They pour over 700 cubic feet of concrete

over the skeleton.

28 days later, the concrete is fully cured.

They move the formwork up a level

to start work on the next terrace.

They repeat this cycle all the way up the tower,

building a new terrace every two weeks.

Now, engineers must find a way to protect residents

and control the powerful winds coming off the coast.

Engineers in Athens are nearing

completion of Greece's tallest building.

Constructing a 50-story tower on this stretch of coastline

presents engineers with a big challenge.

Strong winds threaten to make it uncomfortable for residents

when they use their balconies and terraces.

♪♪

Engineer Kostis Lysikatos and his team must find a way to

dramatically slow down the wind speed

through the open parts of the structure.

It is a luxury residential tower, so the occupants,

they're expecting the best product they could get in the market.

You don't want people to feel that they're gonna be thrown

from the wind.

But on the other hand, you would like to ensure that

you have a continuous breeze coming to the terraces for

the occupants to be comfortable sitting during the hot periods.

Kostis designs different shapes of facade and tests them

in computer simulations to unlock which one maximizes

comfort for the tower's residents.

So we can see the velocity of the wind and as it goes through

here through the spines, we can see that the wind is

reducing the velocity

to be more comfortable for the occupants.

This is how the engineers will apply the solution.

The team seals up the building with 1,000 sliding glass doors

and then installs 2,000 glass balustrade panels to shield

the outdoor living spaces from the wind.

Workers then fix 29,000 aluminum composite

cladding panels to the walls of the tower.

Finally, they embed 38,000 plants across the tower

to form an additional wind barrier.

Together, these features channel wind

up through the center of the tower

and should limit wind speeds on

the terraces and balconies.

Dmitris Chalimos supervises the construction of

this vital part of Riviera Tower.

[Dmitris] The facade in this project is key.

The wind is a key factor

for the design of the sliding door system,

as it can make the doors deflect more than it's allowed

to a point that they can even break.

The window panes in Riviera Tower are made from

extra-thick glass to prevent them from shattering.

Each door panel weighs more than 330 pounds.

They are too heavy and bulky to install by hand.

So, the team uses a special glazing robot to put them in.

The robot's four suction pads attach securely to the pane.

The robot then lifts the glass

and carries it to the door frame.

An operator remotely controls the robot to install the pane

with millimeter precision.

[Dmitris] It would have been very, very difficult to handle

those panels just by hand.

The first panel is in place.

The team then installs the rest

of the door panels for the room.

[Dmitris] We're talking about like very, very heavy doors.

They glide pretty smoothly.

With the sliding doors progressing well,

the team begins installing

the glass balustrades onto the balconies

and fitting cladding panels to the exterior walls.

Workers must now install plants onto the sides of the building

to create an additional wind barrier around the terraces.

The architects of Riviera Tower

designed four walls covered in lush foliage

that reach the full height of the building.

Attaching plant life to concrete creates

a big challenge for the tower's engineers.

Plants need a constant supply of water to survive.

A permanent irrigation system could allow water to seep

through the concrete and corrode

the steel reinforcement inside.

To solve the issue, the tower's designers use

a special green wall system.

[Alexandra speaking]

Alexandra Tsigkouni oversees the team

installing the green wall.

Their task is huge.

Each wall is 656 feet high.

They will be the tallest green walls of their kind ever built.

The team's first task is to cover the wall in a layer of

water repellent membrane.

This waterproofing should protect the rebar

inside the concrete from corrosion.

Workers fix brackets over the top

to hold the membrane down.

Next, they hang special planting baskets made from

fireproof glass fiber.

[Alexandra] This is the planting basket.

It's already filling with soil, waiting to be placed upon

the green wall.

The plants are going to be placed in these locations with

a very, very careful hole in the middle of it.

The team lifts each 44-pound basket onto brackets

and fixes them tightly to the basket below.

It will take workers six months to install the 4,500 baskets

needed to cover all four walls.

Once all the baskets are in place, they'll plant

the green wall to finish the facade.

The completed Riviera Tower

will be the tallest building in Greece

and the centerpiece of a brand-new green city.

It stands as a testament to the ingenuity of the workers

who built it.

[Antoinette] I think this is a transformation for the city.

It's transformation for all the people of Athens as well,

and I think it's actually a defining project in Greece.