All language subtitles for The.UnXplained.S06E07.1080p.WEB.h264-EDITH.7

- A
- mysterious Roman chalice

transformed by light.

A blazing inferno

wielded by ancient armies.

And a 2,000-year-old artifact

that may have
generated electricity.

Today, we tend to
think that modern society

stands at the pinnacle
of technological ingenuity.

But is that entirely true?

The historical
record has revealed

numerous ancient innovations

that were centuries
ahead of their time,

including earthquake detectors,
schematics for flying machines

and weapons of mass destruction.

Is it possible that
our ancient ancestors

were far more advanced
than we realize?

Well, that is what
we'll try and find out.

Within this
modern city lie the ruins

of what was once the
capital of the Roman Empire.

For centuries, Rome was the
most sophisticated metropolis

in the ancient world.

And Roman engineers

also built
breathtaking structures

throughout Europe
and the Mediterranean,

many of which can
still be seen today.

These engineering marvels

have endured the ravages
of time for nearly 2,000 years,

and stand as magnificent
monuments to Roman ingenuity.

The Romans were certainly

the most brilliant engineers
of the ancient world.

When we think of Rome today,
we think of the Colosseum,

we think of the aqueducts,
we think of triumphal arches.

All of them are an emblem
of Roman civilization.

They could discern
effective technologies

and then exploit them
to a much greater extent

than anyone ever
imagined previously.

The engineering achievements

of ancient Rome are well known

and continue to capture
people's imagination.

But is it possible
that the Romans

were even more advanced
than most of us realize?

And could they have
possessed technology

that rivals our own?

The curator of the
Gallo-Roman Museum

announces an extremely
rare archaeological discovery.

Using a metal detector,
a local hobbyist unearthed

a fragment of an
ancient Roman artifact.

This tiny piece of
bronze was once part

of a mysterious object known
as a Roman dodecahedron.

Any discovery

of a Roman dodecahedron
is remarkable and unusual,

because there's not many
more than 100 known to exist.

Generally, a dodecahedron
is a 12-sided item,

and the Roman dodecahedron

was about the size of a
baseball and had 12 sides.

They were hollow
inside and multifaceted,

with different balls or spikes
around the outside of them,

which are very
difficult to create

through molding or construction.

Roman dodecahedrons
have been found all over Europe,

and nobody knows for
sure how they were made.

The craftsmanship
that it would take

to make a bronze
Roman dodecahedron

would have been very challenging

for a metal artisan
to make at the time.

So, it could have
been an example

of the skill of an artisan

to show, like, "Look
what I can do,"

because it was very complex
and bronze was not cheap.

Historians theorize

that Roman engineers may
have fashioned dodecahedrons

using a sophisticated
molding process.

But why did the Romans
go to such lengths

to craft so many intricate
and peculiar pieces of bronze?

What purpose could these
strange dodecahedrons

have possibly served?

What's strange about them
is that there is no record

of what they were used for.

And it's still quite a puzzle
and a mystery to historians,

what function they
actually served.

However, there's a number of
uses that have been proposed,

from tools in
astronomical calculations

to candleholders,

as well as implements
in religious performances.

What they are has been
disputed many times.

And I do veer towards the
very practical explanation,

and that is that it was
a sort of knitting device,

because if you put yarn

around the various protrusions
on the dodecahedron,

you can create a sleeve

or a tube of knitted fabric.

In theory, that is
something really practical

because some Roman garments
are depicted with sleeves.

There is still a huge
amount of mystery

around these very
peculiar objects.

But one of the most
popular theories

is that it had a more
mystical function.

Perhaps it was
used in divination

or sorcery or fortune-telling.

Some historians wonder
whether these objects

were used for forbidden rituals.

Now, if these were indeed
tools for the so-called dark arts,

this raises the question,
is this part of the reason

why there are no
records explaining

what this dodecahedron
was used for?

Whether Roman
dodecahedrons were used during rituals

or for more pragmatic purposes,

they remain a
fascinating enigma,

and suggest that the
Romans' craftsmanship

was far ahead of their time.

Not unlike another artifact
from ancient Rome...

A one-of-a-kind
chalice that features

extraordinary properties.

On a pedestal in
the British Museum

sits an ornate and
mystifying Roman artifact

that is known as
the Lycurgus Cup.

The Lycurgus Cup

is an incredible work
of ancient Roman art

that dates to the fourth
and fifth centuries AD.

It's incredible because
it's part of a rare body

of ancient glass
vessels called cage cups.

Cage cups were
manufactured by a master carver

who very carefully diagrammed

the design he wanted
to cut into the glass

and then very carefully
executed that cutting.

And then that piece of glass
was connected to the inner wall

of the cup, which is why
they're called cage cups.

And the Lycurgus Cup is
one of these rare examples

that were very carefully made,

and only made in
very small quantities.

According to historians,

the cup depicts a mythical
ruler named Lycurgus,

and the artifact
most likely belonged

to an Ancient Roman nobleman

who would have used
the chalice to sip wine.

But what's most remarkable
about the Lycurgus Cup

is what happens to it
when light hits the glass.

The Lycurgus Cup

is made with a
very special glass

that's called dichroic glass.

And what that means is
that when light is bouncing off

the outside of the glass,

the color of the cup appears
to be an olive green color.

But when the light is
passing through the glass

from the interior
through to the exterior,

the glass looks a reddish color.

The Lycurgus Cup is
quite an intriguing artifact

because it's really
one of a kind.

The fact that it has these
very unique material properties

suggested it may have had

some kind of ritualistic
or ceremonial function

and perhaps that interplay
between light and color

may have added some
mystique or intrigue

around these rituals
that took place.

How did the ancient Romans

create a chalice with such
mesmerizing optical properties?

It's a fascinating mystery.
And in recent years,

experts have
discovered that the key

to the Lycurgus
Cup's unique effect

is actually invisible
to the naked eye.

The secret to the
optical behavior

of the Lycurgus
Cup lies in the fact

that there was nanoparticles
of silver and gold

embedded in the glass that
changed the optical properties.

This was one of the earliest...

If not the earliest... examples
of a nanocomposite material.

It's possible that the Romans

might have created
this cup by accident.

That it might have
been a contamination

at the site of where a
glass cup was being made.

But it is also possible

that they knew about this
technology of nanoparticles.

And this knowledge
might have been employed

and used in the
creation of this cup.

The history of the Lycurgus
Cup is shrouded in mystery.

But the glass was created
by these ancient craftspeople

and has survived to this day.

It's a Roman technology
that has stood the test of time.

Does the Lycurgus Cup prove

that the Romans had
a deeper understanding

of science and technology
than we commonly think?

It's a fascinating possibility.

And perhaps further evidence
of ancient sophistication

can be found by examining
a devastating weapon of war

can be found by examining
a devastating weapon of war

that was known as Greek fire.

For four long years,
Arab forces have laid siege to

the capital of the
Byzantine Empire.

But then the Byzantines
risk a daring counterattack

and unleash a
devastating inferno.

Streams of flame shoot
out from Byzantine vessels,

lighting the water on fire

and incinerating the Arab ships.

This fearsome weapon would
come to be known as Greek fire.

Greek fire was one of the
most formidable weapons of its era.

Imagine your ship suddenly
being engulfed in flames

that were almost
impossible to extinguish.

Not only was there this
immense physical danger

but there was also a
massive psychological impact.

The loud roar of the
flames... The sight of it,

the sound of it...
Was really enough

to put terror into
these Arab forces.

At sea, Greek
fire was very useful

because if there's something
a mariner really has a fear of,

it's being set
light to on a ship.

Because there's nowhere to go.

And so, Greek fire had
a terrifying aspect to it,

setting light to ships
and burning people.

Throughout the
Middle Ages, the Byzantine Empire

used Greek fire to strike fear
into the hearts of fighting men.

But how did the
Byzantines develop

such a powerful weapon
of mass destruction?

Greek fire acquired its name

simply because the
Byzantines spoke Greek.

It was quite mysterious
because it was

very quickly established
as a state secret

of the Byzantine Empire.

So we don't have a really
good, clear idea of what

its constituents were or
precisely how it operated.

But we do know that it was a
very effective weapons system.

While the
exact formula of Greek fire

may be lost to history,

experts have proposed
several theories

regarding the composition
of this fiery concoction.

Most scholars agree
that the basic constituent materials

were probably naphtha,
a naturally occurring

hydrocarbon, mixed
with pine resin.

The naphtha provided
the flammability

and the pine resin
thickened the substance

and caused it to burn longer
once it had been ignited.

The secret to Greek fire
being used on water is probably

the addition of quicklime,
which likely gave it

an explosive quality
that allowed it to burn

and have much more
damage on water.

In fact, the water played a
role in perpetuating the reaction

and causing the
burning to increase.

There is certainly speculation
as to the different recipes

for Greek fire, but it
would be very difficult to say

what the classic
Greek fire actually is.

And nobody has
actually recreated it

with perfect accuracy.

It seems that,
just as the Byzantines intended,

the mystery of Greek
fire may never be solved.

But there's another enigmatic
weapon from antiquity

that experts can
examine more closely

because its secrets
are preserved in steel.

For eight long months,
European Crusader Knights,

on a quest to
conquer the Holy Land,

lay siege to this
Middle Eastern city.

In the course of
the bloody fighting,

the Crusaders encounter
numerous Muslim warriors

who wield astonishing,
razor-sharp swords

that are forged from steel
that seems to be unbreakable.

The European invaders
named these fearsome weapons

after a nearby city,
and thus, the blades

became known as Damascus swords.

For the time, the properties
of the Damascus blades

bordered on the edge of magic.

Damascus swords
had extraordinary,

legendary performance
because of their sharpness,

compared to some of
the materials at the time.

They were ten times
as hard on the edge.

They were also
highly superplastic,

meaning that they could
bend extremely and still

spring back into
the original shape.

And this was something that
was observed by the Crusaders.

They saw these
blades that they claimed

could bend 90
degrees, that could

cut silk in half in
the middle of the air.

For anyone who was in a
fight against a Damascus blade,

the behavior of that
sword would have been

mind-blowing to observe.

More than 500 years
after the end of the Crusades,

the remarkable properties
of Damascus swords

continue to inspire
fascination and mystery.

What made these ancient blades

so exceptionally
strong and flexible?

And how were they created?

Curiously, the
answer can be found

not in the city of
Damascus, but rather,

3,000 miles away, in India.

In southern India,

they developed the steel
that was used, eventually,

to make Damascus
swords and blades.

The legends of Indian steel
go back to ancient times.

Over time, via trade routes
around the Arabian Sea,

the Indians were able to move
those materials into Persia,

and that became the center
of trade from which Indian steel

got distributed to
the rest of the world.

It's fascinating
to think that the legendary

Damascus swords trace
their origins back to India.

But how did Indian craftsmen

create such incredible steel?

What did they know that
the rest of the world didn't?

One of the
keys to making high-quality steel

is getting the
material to be very hot,

typically thousands of degrees,

and that was very
difficult in ancient times.

But in India, they had
developed technologies

where they were able
to use monsoon winds

to fuel these fires

and get them to very
high temperatures.

The idea that the
strength of Damascus swords

was forged in the intense
flames of Indian fires is intriguing,

but it doesn't completely
solve the mystery.

Because even with
today's powerful furnaces,

experts still cannot precisely
recreate Damascus swords.

And according to one
theory, the secret may lie

in the raw material
Indian craftsmen used

to fashion their steel.

Iron ores vary tremendously
from place to place.

No two ores are exactly alike.

One theory is that there just
happened to be an iron ore

with just the right
chemical properties,

that happened to
be available in India,

and this was the
real basis for the very

high-quality steel that was
produced from that material.

The reason that the
secret to Damascus steel was lost

is that the ore sources ran out,

and so we can't know
the individual elements

that were in those iron ores.

There is no way for us
to go back in and recreate

the magic that they had done
with those original swords.

While we may never
know how ancient armies

created inextinguishable
flames or unbreakable swords,

we do know that these
extraordinary weapons

we do know that these
extraordinary weapons

struck fear into the
hearts of their enemies.

But not all ancient technology

was designed to
be used in battle.

For instance, archaeologists

unearthed what appeared
to be merely a small clay jar,

but it may have actually been

the world's first battery.

In the basement
of the National Museum of Iraq,

the director of the
museum, Wilhelm König,

stumbles upon
three small artifacts

that an archaeological team
unearthed two years earlier.

He finds a
five-inch-tall clay pot,

a copper cylinder
and an iron rod.

König dates the objects
to roughly 2,000 years ago.

But what's more incredible

is that he theorizes that these
seemingly unremarkable items

might have been
designed to work together

to form an ancient
piece of technology.

Two years later, König
publishes his autobiography

in which he announces his
stunning claim to the world.

He argues that
these three artifacts

may have actually been
the world's first battery.

When
you look at the Baghdad Battery,

it does have the key
components of making a battery,

which is it has two metals
of different properties.

Those are your positive and
negative electrodes, and then

you need a material
between them that allows for

the flow of charge to occur.

That could have been
something as simple as

vinegar or wine or lemon juice.

And so it is
completely reasonable,

with these components,

to presume that
it might have been

a battery of some type.

Is it possible

that the so-called
Baghdad Battery really was

an ancient source
of electricity?

It's a fascinating theory,

and modern scientists
have actually conducted tests

to find out whether
it might be true.

In 1940, an American by
the name of Willard Gray

who worked for

a General Electric
high voltage laboratory

recreated the Baghdad Battery,

and he was able to produce
about a one or two-volt charge.

This is incredibly low.

However, even at
this low-level charge,

there are still potential
uses for this object.

It's incredible that
modern scientists have verified

that this ancient artifact

could have actually
been a working battery.

But what's even more astounding

is that the Baghdad
Battery is strikingly similar

to the first modern
battery that was invented

in the 19th century.

In 1800, the Italian
scientist Alessandro Volta developed

the first modern battery,
which we call the voltaic pile.

This was a groundbreaking
innovation because it was

apparently the first time
that electricity could be

produced and stored chemically.

The voltaic pile consisted
of alternating layers

of copper and zinc
with cardboard soaked

in salt water in
between each layer,

which is actually
remarkably similar

to the materials used
for the Baghdad Battery.

So the idea that an object

that could have a similar
function as a battery

existed 2,000 years
ago is astounding.

And what it really shows us

is that if it were
indeed a battery,

ancient civilizations were
far ahead of their time.

If the Baghdad
Battery was in fact a genuine piece

of ancient technology,

then it naturally
begs the question:

what was it used for?

One proposed use

for the Baghdad
Battery is electroplating.

Whether it's silver or
gold or other metals,

onto jewelry.

It's definitely a
possible use of it,

but this would have
depended on exactly

what electrolyte was used,

how it was
connected to the metal

to cause the electroplating.

So it's not an
unreasonable assumption,

but it would have taken
a little special engineering

around the battery
itself to achieve that.

Another theory
suggests that the Baghdad Battery

was actually used
as a form of protection

for sacred statues of the gods

so that if anyone dared to
touch one of these sacred statues,

they would have received
a mild electric shock

from the Baghdad Battery.

Another theory is

that the Baghdad
Battery was actually used

for medicinal purposes

as a form of mild
electrotherapy.

The Romans and Greeks
were actually using electric fish

to create a form of pain relief.

The ancient Egyptians
also used electric Nile catfish

for treating certain
nerve disorders in people

and also for pain relief.

So it's not unheard
of to consider

that the Baghdad Battery
could have been used

for similar purposes.

While it's fun to speculate
about how the Baghdad Battery

may have been
used in ancient times,

we may never unravel the
mystery of this curious artifact.

Because, unfortunately, it has
once again been lost to history.

In 2003, the National
Museum of Iraq was tragically ransacked

in the chaotic aftermath

of the U.S.-led
invasion of Iraq.

The museum became
a target for looters.

Among the relics
and precious artifacts

that were stolen was
the Baghdad Battery.

There's a lot more
research we could do

to discover exactly
how it worked

but we no longer
have that opportunity.

Skeptics today
obviously dismiss the idea

that the Baghdad Battery
was indeed a battery.

However, the one thing we know

is that the Baghdad
Battery works.

It has been replicated

again and again,

and people have shown

how it does generate current.

And we have to accept

that the ancients
had a technology

which we only rediscovered
in more modern times.

It's fascinating to think that,

when it comes to
harnessing electricity,

ancient people may not have
been completely in the dark.

And there's another remarkable
invention from the past

that also resembles
technology we have today.

This ingenious device,

which was created
nearly 2,000 years ago,

could detect the
tremors of earthquakes

from hundreds of miles away.

Earthquakes...
they are perhaps

the most terrifying
of natural disasters.

Even today, with
modern technology,

we struggle to
predict when or where

an earthquake will strike.

But once these forces
of nature are unleashed,

experts can measure their
power using sensitive instruments

called seismoscopes
and seismometers.

When an earthquake
occurs, essentially, sound waves

travel through the ground

from the epicenter
of the earthquake

and they rock the
ground back and forth.

Modern seismometers
are built to pick up on that.

And that's, in fact, how
we can detect earthquakes.

Measuring earthquakes
immediately after they start

allows quicker evacuation
and rescue efforts

and is certainly useful
in our modern world.

But what if a technology

with the ability to detect
Earthquakes existed

not just in modern times

but 2,000 years ago?

The Han Dynasty
is a sprawling empire

that covers Ancient China
and parts of Vietnam and Korea.

One day, Zhang Heng, chief
astronomer to the emperor,

introduces a mysterious
instrument to court.

He claims his device
can detect earthquakes...

Events considered
by the ancient Chinese

to be important
signs from heaven.

Zhang Heng was an exceptional
figure in Chinese history.

He could be described
as a Renaissance man

that was centuries
ahead of his time.

Zhang Heng developed
one of the earliest instruments

to measure
movements in the earth.

This seismoscope
could be used to detect

certain natural phenomena,
including earthquakes.

Unfortunately, Zhang
Heng's original seismoscope,

which was a precursor
to modern seismometers,

has been lost to time.

However, based on
ancient descriptions

of its general appearance,

historians have created
models of the device

that are on display in
museums throughout China.

In shape, it was a huge urn

which had eight dragons

corresponding to different
directions around the rim,

with their faces turned down

looking at large toads
which had their mouths open,

and when an
earthquake would occur,

the dragon facing in the
direction of the earthquake

would eject a ball
from its mouth,

which would then fall
into the mouth of the toad.

There's an account of it in
the Book of the Later Han,

and it describes how
the seismoscope was

triggered one day.

No one at the court believed
that it actually worked.

But then, a few days later,

a messenger came from
about 400 miles away

reporting that there had
been a massive earthquake.

And everyone at court
was forced to admit

that this seismoscope
could detect earthquakes

hundreds and
hundreds of miles away.

This was an incredibly
important piece of technology

because time was people's lives

when it came to
natural disasters.

It allowed help to
be sent straightaway

to the affected region

rather than having to wait days
for the message to reach them.

This seismoscope
was a technological marvel.

In the rest of the world,
seismoscopes were not in use

and they were
developed in Europe

only in the 17 or 1800s.

So Zhang Heng was numerous
centuries ahead of his time.

Zhang Heng
was clearly a scientific genius.

But how was he able to
build such a remarkable device

centuries before anyone else?

And how did his extraordinary
seismoscope work?

We don't actually
know exactly how it functioned.

There are historical
descriptions

explaining what it looked like,

the general components of it,

but in terms of the
nitty-gritty functioning

of this ancient piece of
technology it's still unknown.

Because both the seismoscope

and detailed specifications
of its inner workings

no longer exist,

experts can only speculate

as to how Zhang Heng's device
may have detected earthquakes.

It's been
proposed, hypothetically,

that within the urn
was a pendulum

which rested on a bronze ball.

When a seismic wave would
come, the pendulum would move

in the same direction
as the seismic wave,

and the bronze ball would move

in the opposite direction
of the seismic wave,

and it would trigger
a dragon head

to release a ball that it
was holding in its jaws.

However, ultimately,
the inner mechanisms

and function of the
seismoscope remain a mystery.

The mystery of how
this odd device detected earthquakes

in ancient times is fascinating.

And almost two
full millennia later,

a team of Chinese scientists
set out to finally prove

how the seismoscope
could have worked.

In 2005, a team of
scientists in China

recreated the
seismoscope successfully,

and the device functioned
as described in the sources.

It had a very high sensitivity

and was able to detect
simulated earthquakes

from about four
to 500 miles away.

Not only was it able to detect
the simulated earthquakes,

it could also identify
accurately the direction

in which they came from.

So from this, they
could conclude

that this seismoscope
was incredibly refined

and advanced for the
era in which it was created.

The Chinese seismometer

was clearly centuries
ahead of its time,

was clearly centuries
ahead of its time,

and it's not the only
instance of ancient people

designing technology
that mirrors our own.

In fact, there was
one Renaissance man

who foresaw a future
filled with flying machines

nearly 400 years
before they existed.

In the heart of
the city stands the Louvre,

one of the most renowned
museums in the world.

Of the hundreds of thousands
of artworks contained

in its prestigious galleries,

the biggest attraction
is the Mona Lisa,

which draws roughly ten
million visitors every year.

The Mona Lisa is one of the
many important paintings created

by celebrated Renaissance
artist Leonardo da Vinci.

But curiously, da Vinci was
much more than just a painter.

He was also a pioneer

who envisioned
futuristic technologies.

Leonardo da Vinci

is widely regarded

as the quintessential
Renaissance man

because he did it all.

He was an artist,

he was a gifted engineer

and he was also
a great craftsman.

So, he had a
wide array of skills

combined with a brilliant mind.

When we think of da Vinci,

we often think
about his sketches

of amazing machines,
and he compiled

this vast collection of
sketches in his notebooks.

He was designing fortifications,

port facilities, canals,

catapults and tanks.

These sketches would
be completely at home

in the notebook of an
engineering student today.

Leonardo certainly had

an amazing imagination.

But one has to say
that Leonardo's ideas

were too advanced for his time,

in the sense that he was stymied

by the lack of the right
materials in the period.

However, the fact that
very few of the things

Leonardo depicted
actually were done

shouldn't really
blind us to his genius.

While most
of da Vinci's concepts

were too advanced to
be built in the 15th century,

incredibly, some traces
of his actual achievements

can be seen today.

Near Florence, a canal system

designed by da Vinci
has been preserved,

and a military stronghold

he constructed in
Switzerland still stands.

But of all the
futuristic machines

envisioned by Leonardo da Vinci,

his most famous designs were
in pursuit of his dream of flight.

For decades, modern
historians have wondered,

did Da Vinci actually discover

the secret to soaring
through the sky

centuries before the
invention of the airplane?

Leonardo's
understanding of flight was

certainly a lot deeper than
many of his contemporaries.

He was one of the first people
to study actual bird motion

to try to figure out how birds
flew under their own power.

If you look at Leonardo's
flying machines,

the first machines that he
envisions in his notebooks

are, in fact, ornithopter
designs, very much like birds,

where they flap their wings
to generate the lift for flying.

And then he
progressed on to designs

which were much
more like gliders.

One of the
really fascinating things

about da Vinci's efforts is he
was very creative in thinking

about how humans might
spin things or turn things.

One of the designs he
had was an aerial screw.

And it's a particular
structure like a propellor,

to provide lift and
have something fly.

Leonardo Da Vinci's principle

of a single screw
turning a propellor

to create lift is
strikingly similar

to the mechanics behind
the modern helicopter.

And over the years,
engineers have been inspired

to bring da Vinci's
visionary designs to life

through real-world
experimentation.

In 1976,

the Gossamer Condor was flown,

and it was he first
human-powered flying machine

with one person operating

this propeller-driven
glider, essentially.

It was the first attempt

at what Leonardo
was trying to make.

A crew at the
University of Maryland

used Leonardo's design
for the aerial screw.

The quadcopter design worked.

The air screws actually
did provide enough lift

to lift the quadcopter up.

And so, there is some
promise for a design like that.

So, Leonardo even today does
inspire people in their designs.

How did Leonardo da Vinci

create technical designs
that remain relevant

more than 500
years after his death?

We may never fully
understand the depths

of his extraordinary genius,

but incredibly, there
are those who believe

that an ancient civilization,

that an ancient civilization,

located in Mexico

might have actually
invented rocket propulsion.

A heavy
rainstorm inundates the ruins

of this ancient metropolis

located northeast
of Mexico City.

Once the weather clears,
archaeologist Sergio Gómez

discovers a mysterious sinkhole
at the foot of a large pyramid

known as the Temple
of the Feathered Serpent.

What this almighty storm did

was to reveal the entrance

into an underground tunnel

that went for around
a hundred meters

directly beneath the pyramid.

A group of around 30 experts,

headed by Gómez, started
to clear out these tunnels.

They came to these chambers

that were full of hundreds
of yellow spheres.

And these were made out of clay,

and this yellow
substance around them

was an oxidized form of pyrite,

so they would have
shone in the light.

Those yellow spheres

are all along the ceiling

and all along the
walls of this tunnel.

If you have a
torch, that torchlight

reflects off of the ceiling.

It looks like the
stars in the sky.

And it's just incredible.

Archaeologists
have also discovered

other puzzling
artifacts at Teotihuacan,

including large
quantities of liquid mercury

and sheets of mica crystals.

What's surprising is
that these materials

are all used in
modern technology.

So what are they doing
in an ancient metropolis

that is more than
2,000 years old?

Because, for
example, mercury is actually used

as a rocket propellant,

this has led many to
suggest that their discovery

may provide evidence for
some form of ancient technology,

perhaps used in propulsion
or in energy creation.

This is very speculative,
but if it were, in fact, true,

we would have to rethink
everything we know

about ancient technology.

Is the presence
of sophisticated materials

at Teotihuacan
just a coincidence?

Or is it really possible
that ancient people

invented an early
form of rocket fuel?

Ultimately, it's hard to say,

because we still have
much more to learn

about the technology
of the ancient world.

Teotihuacan is
one of the most sophisticated,

technologically advanced
ancient sites in the world.

But the big mystery is we don't
know who built Teotihuacan,

and how the ancients
had this knowledge.

This is something that
happens again and again.

We invent something

and instead of
preserving the plans

or the technique, it's lost.

There is still
a great deal of mystery

about ancient technology.

Whole histories of ancient
cultures have been lost.

There's a lot more
research we still could do

to discover forms
of ancient technology

that may have been lost to time.

From enigmatic gold spheres

to incredibly powerful weapons

to devices that warn
of impending disasters,

many ancient pieces of
technology are fascinating

and challenge our
understanding of history.

If we unlock the secrets of
innovations from the past,

could that play a
key role in developing

the technology of tomorrow?

It's an intriguing possibility,

but for now, the mysterious
inventions of the ancients

will remain unexplained.

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