feats of architecture in the history of the world.

Opened in the year 80 CE by the Emperor Titus,

the arena was used to stage gladiator combat, skirmishes

with wild animals, and even mock naval battles

with actual boats.

The unknown architects behind this design

put extensive thought into every detail.

If you've ever wanted to construct your own amphitheater

of death, then this is your lucky day,

because today we're going to take a look at how

the Romans built the Colosseum.

But before we get started, be sure to subscribe to the Weird

History Channel, and let us know in the comments below what

other historical sites you would like to know more about.

Do you want to be entertained?

OK, let the video begin.

[MUSIC PLAYING]

In 64 CE, Emperor Nero built himself

a home, which he humbly nicknamed the Golden Palace.

Clearing the land necessary for construction

meant seizing property from numerous ordinary Romans,

which as you might imagine, wasn't a super popular move.

After Nero died, the empire quickly

cycled through four other corrupt emperors.

Then in 69 CE, Vespasian seized power.

Looking to reverse the damage Nero and his successors

had done to the Roman people's faith in government,

Vespasian lived a more modest lifestyle

and aggressively advocated for Rome's citizenry.

It was around 70 CE when Vespasian promised

to build a public amphitheater, which would

hold gladiator tournaments.

In a politically symbolic move, Vespasian

chose to build this arena directly

on the site of Nero's Golden Palace.

In 80 CE, after 10 years of construction,

Vespasian's son, Emperor Titus, would finally

open the Colosseum.

The venue was inaugurated with a festival

that boasted 100 days of games.

[MUSIC PLAYING]

Vespasian chose to have the Colosseum constructed

on what was once the site of a lake in the garden of Nero's

Golden Palace.

The construction would require drainage

26 feet beneath the surface to divert rivers and streams that

flowed from the nearby hills.

It would also mean the concrete foundations of the Colosseum

would have to run extra deep to prevent collapse.

Dirt that was dug out of the ground

to make space for the large foundation

was repurposed to build up the land around the structure.

This elevated the Colosseum 23 feet above ground level

forcing crowds to look up at rather than down

on the building.

Don't rush off to see for yourself though.

Due to changes in the landscape in modern times,

the Colosseum sits level with the ground.

[MUSIC PLAYING]

The blocks of travertine stone used

in the construction of the Colosseum

were quarried in a place called Albulae, located near what

today is the town of Tivoli.

The site of the quarry was about 20 miles

from the site of the Colosseum, so transporting the blocks

wouldn't be easy.

To help things along, the Romans built a road specifically

for the purpose of moving the stone from the quarry

to the construction site.

Each cart load contained 30 to 50 stones.

And historians estimate workers would have transported

roughly 240,000 carts.

20 to 30,000 people would have been

involved in the construction.

The majority of them were slaves.

[MUSIC PLAYING]

The Roman Empire was an innovator

in the use of concrete to build larger and sturdier structures

than had ever been built before.

The vaults and arches of the Colosseum

were made from concrete, which allowed the massive building

to maintain an open and airy atmosphere, while still

being structurally sound.

The foundations were also made of concrete.

Starting at the outer wall, the foundation

was laid out in concentric circles that

moved inward toward the arena.

The lowest part of the foundation

is roughly 42-feet deep, and it becomes

shallower as it moves inward.

Roman cement was usually made by heating

limestone to create calcium oxide, also known as quicklime.

Submerging the quicklime in water

created a putty that acted as a binding agent in the cement.

[MUSIC PLAYING]

The unknown architect of the Colosseum

wanted the dimensions of the building

to reflect a ratio of five to three,

which was considered ideal at the time.

Indeed, the arena ultimately measured 280 by 168 Roman feet,

and the width of the auditorium and arena

were equal to the height of the Colosseum.

Because of the Colosseum's arches,

the perimeter of the amphitheater had to be exact.

There were 88 entrance arches and each

had to be 20 Roman feet wide and have three Roman feet of space

between them.

For the record, the size of a Roman foot could vary,

but generally it was around 11.5 inches.

[MUSIC PLAYING]

Construction of the Colosseum started with the arches.

Made from sturdy travertine stone,

the arches allowed the laborers to start

work on both the bottom and top of the structure.

Indeed, the upper seating, wooden portico

and walls at the top two floors of the amphitheater

were built simultaneously with the lower

portion of the building.

It was this forward-thinking construction plan

that made it possible for the Romans

to construct the Colosseum in less

than a decade, an absolutely astounding feat for the time.

[SINGING IN ITALIAN]

For the safety of the spectators in the front rows,

the seats closest to the stage were raised nearly seven feet.

In addition, a fence would be placed around the ring

to keep wild animals at bay.

Made from marble and travertine, these seats

were also the most grandly decorated and usually

had ceilings adorned with intricate works of art.

However, as with many modern sports arenas,

as spectators moved further up in the stands,

the seating would become less ornate and less comfortable.

Everyone, except the people in the front rows,

would've been tightly packed in with maybe one

foot of personal space and two feet of leg room.

While that does sound cramped, it's actually more space

than you get flying American Airlines, which

isn't saying that much.

[MUSIC PLAYING]

To remove the waste of humans and animals,

the Colosseum required a sewer system.

The public bathrooms, or latrines,

were a row of holes in the ground

dug over a pipe that carried flowing water,

not fancy, but effective.

The pipe would then empty into a drain

that connected to the city's main sewer, the Cloaca Maxima.

This system may have also provided fresh water

to the spectators, the cisterns placed

to the sides of the Colosseum, which drew water

from the Aqua Claudia aqueduct.

Delivery was accomplished by building lead and terracotta

tunnels in the walls of the Colosseum.

[MUSIC PLAYING]

Within the Colosseum, marble and iron dividers

can be found on the staircases.

Though historians don't all agree as to their function,

some believe that they were intended

to keep spectators separated into their proper socioeconomic

classes, kind of like the border between the riffraff

and the jet set.

I wonder if there was a jet set before jets.

Support for this interpretation lies in the fact

that the highest section in the Colosseum,

where the poorest members of the audience typically sat,

was separated from the rest of the spectators

by a 16-foot high wall.

This seating at the top of the arena,

over 300 feet from the stage, is likely where women and the poor

would have been.

However, many historians have noted

that the five ascending sections in the arena

don't correspond with any known division

of the number of Roman social classes at the time.

This means that if the spectators were seated

by social class, it isn't obvious

how those classes were segregated.

[MUSIC PLAYING]

One of the coolest things about the Colosseum

was its ability to fill with a few feet of water,

so that sailors could hold mock naval battles

in miniature boats.

The transformation though was not easy.

In order to create the aquatic arena,

workers had to remove the amphitheater's floor

and wooden supports.

The arena would then be flooded with water

transported by aqueduct.

After it was all over, the Colosseum

would be drained through a series of runoff canals.

The popularity of these naval skirmishes decreased over time.

Eventually, the wooden supports were

replaced with masonry walls, which

ended the possibility of flooding the floor

and having naval battles in the arena.

[MUSIC PLAYING]

Hypogeum is the Greek word for underground.

And the hypogeum is an area beneath the Colosseum

that was used for a variety of purposes.

Several sections of its walls are carved in unusual ways.

An historian spent many years working out the purposes

of the various carvings.

For example, in the late 1990s, architect Heinz-Jürgen Beste

discovered a set of tracks in the walls

of the hypogeum's hallways and strange diagonal indentations

near some of the entrances to the arena.

Beste eventually concluded that the tracks were likely

used to move animal cages through the hypogeum

during events.

The diagonal indentations allowed

for the placement of ramps that would lead

the animals into the arena.

Beste also theorized that a mysterious series

of semicircular cuts in the walls

were there to allow for the placement of devices

called capstans.

The capstans had four rotating arms

and could be used to lift heavy animal cages from the hypogeum

to the arena floor.

The architect found the locations

of 60 capstans of this type and another 20, which he believed

were used to set up and change scenery.

[MUSIC PLAYING]

Laborers who worked in the hypogeum

received none of the luxuries that the audience

took for granted.

In summer, the poorly ventilated hypogeum was extremely hot.

And in winter, it became cold and damp.

It was also incredibly loud.

The tiny space housed machinery, wild animals

and numerous people who would be shouting to each other.

On top of all that, there were organ and drum cues

that signaled workers to send up scenery or animals,

as well as a boisterous crowd whose footsteps

would echo below.

[MUSIC PLAYING]

For those warm summer days, the Colosseum

was equipped with an enormous cloth awning known

as vela, which would be hoisted over the structure

to shade spectators.

The Colosseum wasn't the only one to use vela.

They were fairly common in ancient Rome

and most amphitheaters and arenas had vela.

The villa at the Colosseum were rigged similarly

to a sail on a ship, making actual sailors the most

qualified people to operate it.

That being the case, the Colosseum

used actual members of the Roman navy

to lift and secure the awning over the crowd.

The job was considered a privilege among the sailors,

as it meant they would get to see a large city, which

most never got the opportunity to do.