Original subtitles

[narrator] Does this bizarre object tell the lost story

of a 4500-year-old war?

For both the party and battle.

So what more do you want in terms of a story?

[narrator] Could this weapon really replace gunpowder with steam?

This gun was designed to fire hundreds of rounds a minute,

and that was unheard of.

[narrator] What was the sinister purpose

of this strange, carved monolith?

[Dr. Marina] They would open the chest, extract the heart,

and make a fire within the chest.

[narrator] These are the most remarkable and mysterious objects on Earth,

hidden away in museums, laboratories, and storage rooms.

Now, new research and technology can get under their skin

like never before.

We can rebuild them,

pull them apart,

and zoom in,

to reveal the unbelievable,

the ancient,

and the truly bizarre.

These are the world's strangest things.

In a cabinet at the British Museum,

is a unique, 4500-year-old wooden box,

from the birthplace of civilization.

There's no other object really like it.

[narrator] For nearly a century, its true purpose has been unknown.

Now, using cutting-edge technology,

we are going to open up this ancient box and reveal its secrets.

This is theStandard of Ur.

A wooden box, nearly 20 inches long,

and eight and a half inches high.

At one end is a peculiar, little doorway,

and its surface is covered in detailed mosaic pictures,

made with polished shell, red limestone, and lapis lazuli.

The result is a truly, beautiful object.

[narrator] And these tiny images seem to tell a story.

Of action, of fighting, but also feasting, celebration.

[narrator] But their meaning is as much a mystery as the box itself.

What is this strange thing?

What do these images mean?

Where did it come from?

The mystery begins in Southern Iraq,

in the ruins of the ancient, Mesopotamian city of Ur.

[Dr. Kevin] Ur is one of the world's earliest cities.

It was founded by the Sumerians, in the area that we call today,

the "Cradle of Civilization."

This is really where things began.

This is where laws began, where writing began,

where farming began.

This is where the beginnings of cities and city states took place.

[narrator] And Ur is at the heart of it.

It was a city that gained tremendous wealth through trade,

so we find a lot of artifacts from Persian Gulf, and Arabian Sea, Asia, India.

So, it was a city that was able to become quite wealthy and even powerful.

[narrator] In the 1920s, renowned archaeologist, Sir Leonard Woolley,

excavates a vast cemetery complex near the ziggurat,

a huge, pyramid temple built from baked mud bricks.

[Dr. Mark] Leonard Woolley finds this group of tombs,

which were quite distinct because they had

many individuals buried in them,

often placed next to each other

and they seem to have been all buried at the same time,

which means that there may have been some form of sacrifice.

[narrator] The tombs are packed with treasures, gold, sculptures,

and precious stones.

It's a sensational discovery.

The 1920s were absolutely a golden age for archaeology.

We have Howard Carter in Egypt,

and Sir Leonard Woolley in Ur,

matching the splendor of what was found in Egypt.

European royalty visited Ur,

even Agatha Christie.

[narrator] In one of the tombs, Woolley discovers

something extraordinary.

[Dr. Kevin] A workman saw a small shimmer,

and began to clear away the earth to reveal a mosaic.

[narrator] It is theStandard of Ur,

or what is left of it after four and a half thousand years in the ground.

The wooden frame has rotted away, but the soil has preserved

the mosaic pieces in place.

By painstakingly filling the voids left by the rotted wood

with plaster and wax,

Woolley is able to secure the mosaics in their original positions,

and to retain the shape of this lost artifact.

So, what we're seeing now is a reconstruction of a very painstaking process.

[narrator] But of all the fabulous treasures found in the royal cemeteries at Ur,

why does this odd box become the most famous by far?

Everything about the decoration

of this enigmatic, 4500-year-old object, shouts success,

because the polished shell, sandstone, and especially the lapis lazuli

are exotic materials from distant lands.

[Dr. Mark] Everything had to be imported

from Central Asia, and Afghanistan, even India.

So it also gives you the sense of the objects themselves reflect the power

and the wealth of the society.

This is a city that's able to accrue

this tremendous wealth and make such objects.

[narrator] It's not just the exotic origins

of the box's decoration that astounds experts.

It is crafted with extraordinary skill.

This is only possible because a previously unseen kind of worker

appears in the first civilizations.

[Jeannette] The food surplus that comes with farming in these settlements,

creates a new type of role in society which is the craftsman.

And because these artisans don't have to go out

and collect food for their families,

they can actually trade their crafts for food.

And you see this increasing skill in everything that they create.

They're making furniture, they're making musical instruments,

weaponry, and even jewelry.

[narrator] TheStandard is one of the finest examples of this work.

And that is one reason why it becomes the poster child

for the lost civilization of Ur.

The other reason is that it's an enigma.

Nothing like it has ever been found before or since.

So just what is it for?

In the 100 years since its discovery,

there's been no shortage of big ideas to explain its purpose.

[Dr. Mark] One idea is that maybe it's a storage device,

perhaps treasure, perhaps in offerings.

There's a little area where you can open this box and then add and remove funds.

So maybe it's a kind of... uh, sort of, treasure box essentially.

[narrator] But something about this idea just doesn't fit.

Because money as we know it has not been invented yet.

[Dr. Mark] Wealth was often assumed to be larger objects,

metals, or food, or grain.

But how are you gonna fit these large and bulky items into a very small box?

[Dr. Kevin] Of course, also, it needs to be said,

that no valuables were discovered inside of it.

This is not a treasure chest.

[narrator] Could these tiny images hold a clue to its true purpose?

One of the two main panels is known as "War."

[Dr. Mark] We see this battle going on, chariots, and troops marching off into war,

and then in another register, individuals getting trounced upon,

these chariots running them over.

And so, both marching into war, but also the people who are defeated

being killed and stampeded upon by the victors.

You also see the king, this large character also prominently displayed

as being victorious in this warfare.

[narrator] When Woolley finds the box, he suggests it is a military standard.

And the name sticks.

[Dr. Mark] Standards are often used in warfare, in particular

as a way of demarcating your side.

The standard is the key symbol which you carry into battle.

So holding the standard is both a signal to your army,

but also a propagandistic tool to your enemies,

that, "We're still here, we're still fighting."

[narrator] And one of the images on the standard looks very familiar.

[Dr. Mark] One of the individuals shown on theStandard of Ur,

looks like there's something similar to that standard,

at least in shape, under the individual's body.

[narrator] Is this an image of a similar standard?

Unfortunately there are a few flaws to this idea.

[Dr. Kevin] One is the size of the imagery,

which would have been almost invisible

from a more than a few yards away.

Second, is the relative fragility of the piece.

And then finally, there is the fact that within its actual construction,

there's no obvious point for the insertion of a pole

to mount it on top of the standard.

[narrator] If it's not Woolley's standard, what is it?

What is this 4500-year-old object actually for?

For decades, experts have been studying

these intricate mosaics in search of the answer.

On the opposite side to the War panel, is the one called, "Peace."

The Peace side is showing a kind of banquet,

a kind of celebration.

[narrator] Zooming in on this digital reconstruction,

reveals a possible clue to its purpose, hidden in plain sight.

The upper register is the most interesting.

Here we see a large figure, we assume that this is the king.

Before him are arrayed a group of sitting officials, raising glasses with the king.

And beside them there is a musician playing a lyre.

[narrator] The theory is that theStandard of Ur is actually a sound box for a lyre.

[Dr. Mark] The most ancient lyre that we know of is about 3200 BCE

found in the same region, in ancient Sumer, which is southern Mesopotamia.

So this is a region where such a musical instrument was in fact invented.

[narrator] The similarities between theStandard of Ur

and a lyre found in a tomb at the same excavation, are striking.

[Dr. Mark] It's possible that this is a lyre, because both of 'em

have a box-like middle, with extensions where the strings would be.

And the hollow inside the box could make a musical sound

when it's strummed up with strings.

[narrator] So is that the answer?

Is this the sound box of the king's lyre?

This is an attractive notion,

but there's one big problem with it.

If this is a sound box, it has been coated with bitumen,

and with stone and shell, which would have had a considerable damping effect,

effectively rendering it useless as a sound box for a stringed instrument.

[narrator] There is one final explanation for this strange box.

For years, the assumption has been that these are symbolic images,

representing a well-balanced society.

An advertisement in effect for how civilizations should run.

[Dr. Mark] One is the war-like aspect that's necessary to maintain power,

and the trade connections that war would have had.

So war is a necessary component of that, in asserting power.

But at the same time, a society enjoys its fruits, its economic benefits,

and the partying, and the feasting that you would have

as a way to affirm the loyalties you have to the king.

And the king's, also, power as... as someone who gives his people these great feasts.

[narrator] But experts now suspect,

the events depicted could be a real historical event.

[Dr. Mark] What we're seeing is a story where there's a prominent battle

in the time of the king.

And he was ultimately victorious,

and when you win in battle, what you do, you usually celebrate.

You're showing the actual battle happening one side,

and then on the other side you show the feasting that would occur

after the battle, that you're celebrating your great victory.

[narrator] An advertisement of victory fits

with the small size, and the intricate, delicate decoration.

[Dr. Kevin] It's unlikely that such an elaborate object

would've been truly functional.

It would've been largely for display.

[narrator] So perhaps this strange box once sat on display

in one of the first cities on Earth,

purely to remind people of a great success in battle

of Ur's powerful king.

Both a party and battles,

so what more do you want in terms of a story?

[narrator] The one thing we're certain of,

is that theStandard of Ur is a unique and beautiful snapshot

of an ancient, lost civilization.

At London's Royal Armoury Museum,

is an unknown and very deadly gun.

What we're looking at here, is the 19th century version of a weapon

of mass destruction.

[narrator] Now brought out of the shadows

and painstakingly reconstructed...

this is 170-year-old machine gun,

powered by steam.

Who would've thought that steam could challenge gunpowder?

[narrator] Almost five feet long, it is made of iron,

with a wooden crank handle, and a bizarre brass funnel.

[cranking]

It might look odd but it is one of the most devastating weapons of its time.

This gun was designed to fire hundreds of rounds a minute.

Some say even up to a thousand,

and that was unheard of.

[narrator] But did it actually work?

How did it work?

And why would anyone want a machine gun powered by steam?

This was an era when everything was being converted to steam power.

It just seemed like steam was this panacea

that you could use to make any task easier.

[Dr. Sarah] It was the driver behind the Industrial Revolution.

Factories and mills which used to be powered by water and horsepower,

were now powered much more efficiently by steam.

[narrator] The possibilities seemed endless.

[Dr. Sarah] Steam had so much potential

that everyone was turning to it as a new source of power,

from pragmatic things like steam powered tractors,

through to really quite crack-pot inventions.

One of the oddest is the idea of a sort of steam powered automaton.

Like a giant metal soldier that would pull along a cart of people.

[train whistling]

[narrator] Steam powers everything, except guns.

Until this mad contraption is created.

But who comes up with such a bizarre device?

This outlandish, 19th century invention is the steam gun.

The man who dreams it up is, prolific, American engineer, Jacob Perkins.

By the time Jacob Perkins arrives on British shores,

he already has a seriously impressive track record.

[Dr. Andrew] He'd invented just a whole range of different inventions

from devices to measure the speed of ships,

to a technique for plating buckles.

That was his first invention at the age of 15.

He really was born to be an inventor.

[narrator] While in England, Perkins catches the steam bug,

and hits on an extraordinary idea.

[Andrea] As part of his work, Perkins designed some really high pressure boilers

pushing the technology to its limits. And of the things that he sees,

is that when he releases the pressure a bit,

he can observe little particles fired at great speed,

and that gives him an idea.

[narrator] Perkins begins to design a revolutionary steam powered gun

hoping to sell it to the British military.

Over the years, his son, Angier, develops and improves it,

culminating in 1851, in this.

But this extraordinary contraption won't be an easy sell.

The problem with selling his invention is that

they already know how to fire a gun.

I mean, gunpowder and propellants already exist.

[narrator] Since its invention over 1,000 years ago,

nearly all firearms are powered by gunpowder.

It was invented in China,

and it's just salt, pewter, charcoal, and sulfur, very, very finely ground.

And the things is that when you ignite it...

[crackling]

...it burns incredibly fast,

and produces huge amounts of gas.

And so what you've got is a pulse of gas that can really push a bullet or a cannonball.

[narrator] Gunpowder is a winning formula.

So why does Perkins want to swap it for steam?

By the time Perkins arrives on British shores in 1819,

recent conflicts had shown that even gunpowder has its problems.

In the decade before Perkins invented the steam gun,

Britain was heavily involved in the Napoleonic War,

to try and prevent Napoleon from advancing his empire across the whole continent.

[narrator] Napoleon's tactics proved brutally effective against British fire power.

Napoleon's strategy relied on speed, momentum, and mobility.

-[horse neighing] -[Dr. Sascha] Whereas, the British favor

a large number soldiers spread out in a relatively thin line,

to all fire in one direction.

Napoleon opts for the column formation.

Narrower, but deeper, and this favors forward movement.

[soldiers yelling]

[narrator] The French are fast, the guns facing them are anything but.

[Dr. Sarah] If you're fighting on the British side,

you're most likely carrying a musket.

And that musket probably would've been one called, the "Brown Bess."

[narrator] These muskets use a ball and a paper cartridge filled with gunpowder.

Reloading one of these muskets is a quite laborious process,

'cause every part of what you're doing is separate.

You have the gunpowder, you have the tamping between the powder and the ball,

you have the ball itself, which has to be loaded in separate.

You gotta be careful, because it's a ball, and it can roll back out again

if you handle it poorly.

And then to fire the musket, you have to cock it.

And then you gotta start the whole process all over again.

[narrator] Reloading and firing just once can take 20 seconds,

and even when you fire chances are you miss.

Muskets aren't just slow,

they are hopelessly inaccurate.

[Dr. Andrew] Because the musket was loaded from the front,

the balls were made intentionally, slightly smaller

than the barrel to allow them to be easily passed inside.

But that means they can jiggle around inside the barrel

and come out in all kinds of different angles.

[narrator] Perkins is convinced that his steampunk invention

is not only faster but more accurate.

His problem is that history is already littered with strange weapons

trying to solve the same issues,

and mostly failing.

Some add more barrels to the gun so they can be fired all at once.

[Dr. Andrew] You can concentrate your fire in a single shot,

but ultimately it doesn't solve the problem.

First off, they're still just as inaccurate

as the individual barrels that they are made of.

And secondly, although you can fire lots of shots at once,

they then take even longer to reload.

Obviously, as many times longer as you have barrels.

[narrator] Other weapons try a rapid loading mechanism.

Back in the 2nd century BCE, the Chinese developed a repeating fire crossbow

that used a little magazine that could drop ten bolts

into position to fire in 20 seconds.

[narrator] But a rapid firing mechanism in a gunpowder weapon

is altogether more complex.

One of the problems with using gunpowder,

especially if you're trying to fire again, and again, and again,

is the gunpowder burns hot.

And so your gun will gradually get hotter, and hotter, and hotter.

Until, eventually, the metal will actually soften,

and the gun itself will deform.

[narrator] Perkins believes the answer to all these problems

is to do away with gunpowder altogether,

and replace it with steam.

But is that just a pipe dream?

This odd, 19th century contraption is the Perkins' steam gun.

But he isn't the first to dream up this idea.

[Dr. Andrew] Back in the 15th century, Leonardo da Vinci

who seems to have invented basically everything in his sketch books,

had drawn an unusual picture, of what looks like a steam powered gun.

[narrator] He calls it, the "Architonnerre."

[Dr. Andrew] And actually, da Vinci attributes this idea

to the ancient Greek scientist, and polymath, Archimedes,

who lived in the 3rd century BCE.

Which means, the idea of a steam gun

could date back over 2,000 years.

[narrator] The Architonnerre uses a coal fire to generate steam

by heating the gun itself.

Perkins uses his own state of the art boiler

operating at extremely high pressure.

And his original machine is designed to take full advantage of it.

[Dr. Andrew] There's a six foot, or two meter long, smooth ball barrel,

and at one end, there's a magazine, which just using gravity

feeds balls into it.

[narrator] The gun is connected to a high pressure steam boiler.

[Dr. Andrew] By opening the valve, you can allow the pressurized steam

into that barrel which fires those balls out the end of the gun.

[narrator] Perkins' son, Angier, improves on the original 1824 design,

giving it more precise control.

In Jacob Perkins' original design, the balls were just falling into the gun

under the force of gravity.

Whereas his son, Angier, extended it,

and made it a slightly more controllable design.

What that meant was that by turning a handle, you are cranking two pins,

which would allow each ball to fall into the barrel individually.

And then, as the crank continued to turn, it would open a valve

which would blast that steam pressure through and fire

the thing out the end of the gun.

And then that cycle repeats, as fast as you could crank it,

it would carry on firing.

[narrator] Is steam about to trump 1,000 years of gunpowder supremacy?

[narrator] In 1824, after five years of work,

Jacob Perkins is ready to demonstrate his original steam gun

to the top brass of the British military.

Front and center is none other than the Duke of Wellington himself,

who is now Master General of Ordnance,

responsible for evaluating and procuring new weapons for the entire army.

[narrator] Under Wellington's gaze, Perkins' bizarre contraption

is subjected to rigorous tests of speed,

power and accuracy.

If Wellington was looking for a fast-firing weapon,

this steam gun delivered.

The ports differ quite widely,

but at the lowest end of the estimates,

it was said to fire 250 rounds a minute.

And up at the top end, people claimed 1,000 rounds a minute.

So, if you think about the comparison with a musket,

which was firing just four times a minute,

this is anywhere from 60 to 250 times faster.

[rapid gunfire]

[narrator] The steam gun is not only fast,

it's deadly accurate.

[Andrea] One of the things about using steam

is that it's incredibly clean.

All you've got is H2O.

And you'll not be left with any of the residues

that you might get with gun powder.

So you can design your steam gun to much higher tolerances

and you'll get better accuracy

than you can with just a conventional musket.

[narrator] And unlike a gunpowder firearm,

there is no risk of the barrel deforming.

[Andrea] When you generate the stream,

it's gonna be only 100 or 200 degrees

above the boiling temperature of water.

And that's going to be as hot as your gun will ever get.

And so you could fire over and over again

and you're never gonna overheat.

[narrator] But can Perkins' steam gun pack enough punch?

Perkins cranked up the boiler to full pressure, 900 PSI.

And he demonstrated it over a range of 100 feet.

He could smash a hole in 11 one-inch planks.

[rapid gunfire]

[narrator] Perkins' strange contraption proves

that steam can power a weapon of extraordinary speed and accuracy.

It should be an unmitigated success,

but things don't quite go to plan.

Even after years of tests and refinement by Perkins' son Angier,

the British forces just aren't interested in it.

They refused to purchase his device,

and it ends up being just kind of a demonstration piece.

[narrator] So what goes wrong for this bizarre gun?

The first obstacle is a military bogged down by tradition.

[Dr. Sarah] The British Army at that time

were not considered to be early adopters.

So improving on traditional techniques,

yes, that was accepted,

but the idea of moving from gunpowder to steam,

that was just too radical.

[narrator] The second problem is a whopper.

[Dr. Andrew] In order to fire this thing,

you needed a five-ton steam boiler

to be lugged around with it at all times.

This is an incredibly risky device to be dragging around the battlefield.

-You got this enormous pressurized steam boiler. -[kettle whistling]

It's basically a bomb.

[narrator] The final problem

is by the time Angier perfects his father's steam gun,

gunpowder technology has moved on.

They got rid of paper cartridges

and managed to come up with brass cartridges

to store the gunpowder on the back of the bullet.

And bullets were also becoming pointed,

which means they were much more aerodynamic.

That meant much, much higher speeds,

much longer range,

and critically, much greater accuracy.

And that means the problems that the steam guns were hoping to address

were being solved, and better, with gunpowder-based technology.

[narrator] Perkins' creation doesn't stand a chance.

So, is that the end of the steam-powered gun?

Not quite.

[narrator] Despite its speed and power,

this weird 19th century steam-powered weapon

just can't compete with gunpowder.

But more than 100 years later,

the British Army finally find a home for Perkins' revolutionary ideas.

[Dr. Sascha] In the 1940s,

anti-aircraft guns were sometimes redeployed

from merchant ships onto British warships,

leaving the former quite unprotected from aircraft attack.

With gunpowder in somewhat limited supply,

the Department of Miscellaneous Weapon Development

turned to a resource that was readily available on ships...

steam.

[narrator] Enter the Holman Projector.

[Dr. Sarah] The Holman Projector worked by connecting pipes

to the ship's steam boiler.

Then a grenade was dropped down the barrel,

and the pressure from the steam would shoot the grenade out.

And this effectively functioned as an anti-aircraft weapon.

It was an unrifled gun,

and that meant that you could throw anything down there.

So if you didn't have a grenade,

you had the option of a cabbage, a can,

or apparently, the biggest favorite was a potato.

[narrator] Making it the world's first anti-aircraft spud gun.

And just as Perkins predicted,

it is lethal.

[Dr. Sascha] There are reports

that one sailor on a merchant ship called theHighlander,

successfully downed a German aircraft using a Holman Projector.

It's not clear from the reports

whether or not he fired a potato at it.

[narrator] Finally, the steam gun has its day,

albeit almost 120 years after Jacob Perkins has the idea.

In Mexico's National Museum of Anthropology

is a strange monolith from a lost world

with a violent past.

The civilization that created this object was almost wiped from history.

[narrator] Now, we're bringing every detail of this astonishing artefact

out into the light.

This is the Teocalli Stone.

Cut from volcanic rock,

it stands roughly four feet tall, three feet wide, and three feet deep.

It effectively looks like a model version of a temple.

[narrator] But carved into every surface are disturbing images,

eerie figures with skull-like faces,

weird animals, plants, and monsters.

They all hint at a gruesome and violent past.

Waging sacred war in order to have the human sacrifices

to, to offer the sun.

[narrator] Is this a sacrificial altar?

[Dr. Marina] They would open the chest, extract the heart,

and make a fire within the chest.

[narrator] Or are we simply misreading its purpose?

Just so many different clues that can be read in different ways,

and you have to really read closely and piece them together

to figure out what it's all about.

[narrator] What becomes of the legendary leader it is created for?

And could it really have anything to do with human sacrifice?

1926, Mexico City.

A mysterious object is unearthed

from the foundations of the National Palace.

They knew about this object before,

but it was only in 1926 that they dug it up

and it was able to be examined fully for the first time.

[narrator] The strange shapes on the back of this monolith

point archaeologists toward its legendary creators.

[Jeannette] You see these carvings with an eagle

with its wings widespread on top of a cactus.

And that's an image that most people in Mexico would recognize today

as it's on the Mexican flag.

[narrator] It is a 13th century legend.

A group of migrants are traveling through the Valley of Mexico.

They are about to transform Central America.

[eagle squawking]

There was a prophecy that said that the capital would be created

when an eagle was seen standing on a cactus in the middle of a lake.

And this would end up being Lake Texcoco

in what is now Mexico City.

[narrator] Archaeologists know exactly whose legend this is.

[Jeannette] Without any doubt,

this monolith was created by the Mexicas of Tenochtitlan.

[narrator] The Mexica have a more familiar name for many,

the Aztecs.

Mexico City is built on the side of their vast capital, Tenochtitlan.

The modern National Palace in Mexico was actually built

on top of where the palace of the ancient rulers would have been located.

Therefore, this monolith found in the foundations of the National Palace

probably belonged to an important figure that lived in that palace.

[narrator] Who is this figure?

Can the eerie images at the top identify him?

[Dr. Marina] On the left, is the god Huitzilopochtli

which is a god that is associated with kingship.

And on the right is the god Tezcatlipoca

who was the god of night,

but also a god that was associated with warriors and with kings.

[narrator] But these strange carvings reveal more than Aztec gods.

They could also narrate historical events

and represent real historical figures.

So the figure on the right might also be a real ruler.

[narrator] This image holds clues to the identity of that ruler.

[Caroline] It shows a diadem, a little crown,

and a nose plug,

And those are symbols of rule in Aztec culture.

[narrator] Experts believe this all points to one person,

the most legendary and ruthless of all Aztec leaders.

In other pictographic sources,

those symbols are often associated with Moctezuma II.

[narrator] And they don't come bigger than Moctezuma II.

He ruled from 1502 to 1520,

taking the Aztec Empire to the height of its power,

ruling over 5,000,000 people across 80,000 square miles.

Moctezuma II is this almost mythical figure.

He had this enormous zoo,

and there is evidence for this.

He has great luxury that he lives in.

Supposedly, he has hundreds of wives and children.

He's a figure that not only has enormous power,

but goes to great lengths to promote himself

as a figure of power and authority.

[narrator] An object of extraordinary craftsmanship,

made for the greatest leader of one of the most remarkable civilizations of the Americas.

What is the purpose of this strange thing?

[narrator] This strange monolith

is created for the fabled Aztec leader Moctezuma II.

But what is it?

[Jeannette] The shape of it.

The lines representing steps.

It's unmistakable when you compare it

to known temples of the period.

It effectively looks like a model version of a temple.

[narrator] Scale models of temples are not unusual in Mexica society.

But there is something strange about this one.

[Dr. Marina] Across the empire, we have been able to find smaller models.

[narrator] These scale models are usually just a few inches tall.

None of them are as large as this one.

[narrator] The four-foot tall Teocalli is a giant in comparison.

Some experts think there's a very good reason for its oversized proportions.

[Dr. Marina] On top of some of these models are gods sitting on them

as if they were sitting on thrones.

So the Teocalli is not just a representation of a temple,

but the throne for a god.

[narrator] The Teocalli is now known by another name,

the Throne of Moctezuma II.

But there is a problem with this idea.

In this period, thrones were most usually made of reeds.

It's not a chair society.

You sat on a fabulous reed mat.

I think it's unlikely that Moctezuma actually sat on it.

[narrator] Some scholars believe it could be a symbolic throne,

a token of power,

rather than a real one.

But close examination of the other bizarre symbols

reveals a much more disturbing explanation for this strange thing.

Experts believe this circle at the top of the monolith is a solar disc.

A calendar that charts the 52-year Mexica cycle of life and death.

[Jeannette] According to Mexica traditions,

the sun had already been swallowed up four times prior,

and during Moctezuma's reign,

this was the fifth sun.

And in order to ensure that the sun always comes back up after night,

you have to appease it with blood sacrifice.

And that's what the symbolism there is about,

waging sacred war

in order to have the human sacrifices to offer the sun.

[narrator] This idea has given the monolith a second name.

[Jeannette] When renowned Mexican archaeologist Alfonso Caso

first sees the monolith,

he names it the Teocalli de la Guerra Sagrada,

which in English means Temple of the Sacred War.

[narrator] And other mysterious symbols carved on the monolith

can narrow down exactly when this strange relic is made

and exactly what it is for.

On the front of the monolith are two date glyphs.

One rabbit.

And two reed.

And those symbolized 1506 and 1507 in our modern-day calendar.

[narrator] These dates point to the most critical event

in the whole 52-year Mexica calendar...

the New Fire Ceremony.

It has just one goal...

preventing the end of the world...

through human sacrifice.

The priest would congregate on a temple

and sacrifice a victim.

They would open the chest,

extract the heart,

and make a fire within the chest of this victim

that would symbolize the creation of the new fire of the new era.

If the fire worked,

that indicated that everything was going to go well.

If it didn't work,

then it was the end of the world.

[narrator] To the people who made this strange object,

human sacrifice is actually about preserving life.

It wasn't seen as a punishment or as a vengeful action.

In fact, the gods demanded this blood sacrifice,

and the ruler had a responsibility to provide human sacrifice

in order to ensure the survival of your people.

[narrator] But rather than simply commemorating Moctezuma's New Fire Ceremony,

could this bizarre stone monolith

have played a vital and bloody part in it?

We think of altars as being big tables.

But Aztec sacrificial altar is actually quite pointed,

similar to the top of the Teocalli,

because the way that sacrifice is most often conducted

is that four priests hold the arms and legs of the person

and pull them back to stretch the chest up

so that they can easily remove the heart from the chest cavity.

There isn't any residue of blood as far as I know.

But it's not impossible it was a sacrificial altar.

[narrator] Is this extraordinary object

the last thing victims see before their hearts are torn out?

Or is it simply a throne for a legendary leader?

For now, its true purpose remains a mystery.

One thing we do know

is that whatever the outcome of Moctezuma's New Fire Ceremony,

it does turn out to be the end of the world.

[thunder rumbling]

In 1519, barely a decade after Moctezuma's New Fire Ceremony,

the Spanish conquistadors arrive.

[Caroline] Hernan Cortes besieges Tenochtitlan.

And what happens then is the most incredible destruction

because the Mexica refused to surrender.

So Cortes ends up having to advance through the city

destroying buildings as he goes.

It's an absolute massacre.

[narrator] Moctezuma II's life ends in tragedy.

And so does the Mexica Empire.

[Caroline] Ten years after the Spanish invasion,

something like 90% of the Aztec Mexica people

are dead either through violence or disease.

It's the most astonishing decimation of populations.

[narrator] And the Christian invaders rewrite Mexica history

to create a highly exaggerated bloodthirsty legend.

[Caroline] Because the Spanish are so obsessed with human sacrifice

as a justification for the conquest,

and because it seems so alien to us now,

we often see the Aztecs through this narrow lens of sacrificial violence.

We seem them as this bloodthirsty culture.

But the reality is that they believe

if they don't sacrifice humans to the gods,

the world will come to an end.

[narrator] The truth behind Mexica ritual

is buried in the conquistadors' obsession with sacrifice...

just like this mysterious monolith tribute to a godlike king...

which ends up lost beneath the foundations of Mexico City.