Original subtitles

- Tonight, one of the most puzzling

archeological sites on Earth.

- Machu Picchu is a very mysterious place.

Why build a city here?

- People keep digging for answers,

and for some it's even become an obsession.

- 500-year-old secrets hidden in skeletons and stone.

- Some of the skulls that were found didn't even look human.

- It could be the most important archeological find on Earth.

- You look at these single stones

and see how perfectly they're fit.

There's not a good explanation

for how people were able to do that.

- Now, we explore the top theories surrounding one

of the ancient world's most enduring riddles.

- How did they develop

such an accurate understanding of time and space?

- Some people think that there's a much more ancient history

to Machu Picchu we're unaware of.

- Who built this astonishing complex and why?

[mysterious music]

- [Laurence] It's the morning of July 24th, 1911.

Deep in the jungles of Peru,

Yale University Professor Hiram Bingham is

on a quest to find an infamous lost city.

- There's a story from 400 years ago

about the end of the Inca Empire,

when the Spanish came in and took them over,

that they took all of the king's gold

and hid it in a place that is called Vilcabamba.

And that has become a myth called

the lost city of Inca gold.

- By the turn of the century,

as far as historians were concerned,

Vilcabamba was like Atlantis.

It was a fairytale.

Hiram Bingham disagreed.

He wasn't a trained archeologist.

He was a professor at Yale, but he believed very deeply

that Vilcabamba existed and that it could be found.

- There was still persistent talk

by the time Bingham made his first journeys

to Peru, about this lost city,

where there was a huge stash of Inca gold.

- When Bingham arrives to Peru in 1911,

he meets with a Peruvian scholar who suggests

that he's seen in maps, information

that there are a series of very impressive Inca sites

along the Urubamba River.

- [Laurence] Beginning on July 19th, 1911,

Bingham's team bushwhacks its way

through perilous jungle terrain,

determined to find the lost city.

- He has to this deadly river,

and then up this steep, jungle-covered hillside

that's infested with poisonous snakes.

- When he finally reaches the top elevation,

he's expecting something that would be striking immediately.

And it's just essentially a farm.

It doesn't have the immediate gut punch

that he was looking for.

- [Laurence] That is, until he turns a corner

and takes in a shocking sight.

- He can tell that

there's approximately 200 stone structures

that are buried underneath the foliage.

- Bingham is somewhat impressed by the site

that is nevertheless still covered by the forest.

It's unclear to him what is it exactly,

but he senses that this might be the lost city of the Inca.

- It could be the most important archeological find on Earth.

- [Laurence] Bingham and his team go on

to uncover five square miles of what are Inca ruins,

dating back several centuries.

Locals tell Bingham the site is called Machu Picchu.

- The Inca are really well known for their incredible stonework,

which is called ashlar masonry,

and the stones fit together perfectly without any mortar.

It's almost like a jigsaw puzzle.

They did not have the advanced technology

that we have today, so it's really a marvel.

- You cannot fit a dollar bill or a razor blade between them.

The technique of fitting these blocks together

baffles archeologists and engineers today.

- [Laurence] Bingham marvels at the structures

that kept Machu Picchu standing for so long,

and wonders if these ruins could be Vilcabamba.

He also notices that a grand plaza separates

the agricultural terraces on one side

and a grid of closely-packed buildings on the other.

- There's a lot of different kinds of architecture

on the site, which suggests that it was used

for a lot of different purposes.

- Machu Picchu is a very mysterious place.

Why build a city here?

Was it an outpost?

Was it a secret agricultural place?

- Because the Incan people had no written language,

we have to rely on what record keeping was kept

by the Spanish conquistadors.

So what took place in Machu Picchu,

what it was used for, remains a mystery to us.

However, Hiram Bingham does have some ideas.

[tense music]

- [Laurence] The Inca Empire was founded

in the early 15th century

by a king named Pachacuti.

- Pachacuti is known

as the Alexander the Great of the Inca Empire.

He's the one that started to expand the Inca state

from being a very small state centered in Cusco,

just suddenly exploding like a supernova across the Andes.

- [Laurence] What started as a tribe

of around 100,000 people

grew over the next a hundred years into an empire

of more than 10 million,

stretching over 2,500 miles from north to south.

- The Incan Empire excels at government,

architecture, agriculture.

And the Incan Empire was celebrated

for the rumored abundance of gold.

- [Laurence] Inspired by rumors of treasure,

Spanish conquistadors arrive in Peru in 1532.

- The Inca Empire will never be the same.

There's no competing with the horses,

with the guns, and the disease.

Smallpox ended up killing 90% of the native population

in all of the Americas.

From the Spanish records,

we know that the last Inca king retreated to Vilcabamba

with about 100 people,

and they evaded Spanish invasion for nearly 40 years.

- [Laurence] Based on Machu Picchu's

nearly inaccessible locale,

this seems like the perfect spot

to hide treasure and people.

- The longer Hiram Bingham studied this site,

the more apparent it became that a large number

of people lived and died at Machu Picchu.

- During Bingham's first expedition,

he only spent a day up at Machu Picchu.

He didn't know what to make of it,

but he came back for two more expeditions

and started doing excavations at Machu Picchu

for the first time.

What is this?

Could this possibly be Vilcabamba?

- [Laurence] Bingham unearths large burial sites.

What he finds appears to confirm his theory

that he's found the lost Inca city.

- Upon examining these graves,

Hiram's team determines

that over 80% of them must be female.

- Through that, he hypothesized

that this was one of the cloisters of chosen women.

- The Incas had a group of women called

the Virgins of the Sun.

They'd find a girl who was pretty and perfectly formed,

and they would take her to this kind of a convent

when they were about 10 years old.

- Bingham believed that this was Vilcabamba

and that the last emperor retreated there

with these Virgins of the Sun.

And in 1913, "National Geographic" devotes

an entire issue to this incredible find.

- But Bingham's crew does not find

the legendary stores of gold that they were looking for.

- [Laurence] Despite his disappointment

at the lack of treasure,

Bingham is convinced that Machu Picchu is indeed Vilcabamba.

He even writes the 1948 memoir about the lost city

that becomes an international bestseller.

- Until his death in 1956, he continued

to argue Machu Picchu must have been

the last lost city of the Inca.

And it's said that he may have been one

of the inspirations for Indiana Jones.

- [Laurence] But by that time, a growing number of historians

and archeologists believe Bingham's wrong.

- Bingham's expert took a look at the skeletons,

and they looked thin and small

and he concluded that they were women.

But these were indigenous Quechua people

who are slight of build.

- More recent studies have shown that there was, in fact,

a fair balance between men and women.

- Even more importantly,

the Spaniards had sacked Vilcabamba

and they burned the whole city.

But Machu Picchu was pristine.

There was no ash, there was no burned anything there,

so it didn't seem to fit.

- [Laurence] Bingham's theory seems to hit a dead end

in 1964, when American explorer Gene Savoy

reveals the true location of the lost city of Inca gold.

- Gene Savoy excavates a site called Espiritu Pampa,

which was a site that Bingham had actually traveled to,

but Bingham dismissed it.

In fact, he did not go far enough

into the ruins to realize how large it was.

Gene Savoy was able to do enough research

to realize that the Espiritu Pampa was Vilcabamba,

the actual lost city of the Inca.

- [Laurence] Savoy has found the true Vilcabamba,

but alas, no gold is found there either.

- According to the Spanish records,

when they did finally find Vilcabamba,

they melted down every gold

and silver thing they could find.

- [Laurence] If Machu Picchu isn't

the lost city of Inca gold,

then what could it be?

- You can't deny the strategic location of the site.

It's very high up on the mountains,

surrounded by the river on basically three sides.

[tense music]

- [Laurence] For almost all of its 100-year existence,

the Inca Empire is at war

either with neighboring tribes, Spanish invaders, or both.

- The Inca Empire was a patchwork

of other cultures that they absorbed.

Some of them were in an almost constant state of rebellion.

- [Laurence] Machu Picchu's remote location

makes it easily defendable.

- The access to Machu Picchu is very limited.

There's a formal entrance

where there was a very narrow path cut

into the side of a cliff.

At one point, there's a bridge.

Below is thousands of feet,

so if you fall, you die.

- And once the planks are removed off this bridge,

the access to Machu Picchu is completely cut off.

- And attempting to scale the cliffs below

would present an incredible disadvantage against

anybody who wanted to siege the city.

- Machu Picchu has such a unique strategic position,

located on the edge of the mountains in the rainforest,

which means it can watch three boundaries at the same time.

- So if you wanted a first line of defense,

that's where you'd put your citadel.

- [Laurence] Even so, some historians note

that Machu Picchu architecture isn't typical

of Inca military outposts.

What's inside the many grave sites raises further question.

- The Inca were known for burying their dead

with implements that were important to the person

during their life.

But we don't see anybody buried with implements of war

or skeletal injuries that would be related to war.

And so a military fortress probably was not

the main purpose of the site.

- [Laurence] Ever since Hiram Bingham introduced

the modern world to Machu Picchu,

scholars have puzzled over its purpose.

- Because the site is so interesting

and still so well preserved,

people keep digging for answers

and for some it's even become an obsession.

- [Laurence] In 1987, one expert searching

through historical archives

in the former Inca capital of Cusco, Peru

makes an amazing discovery.

- The Inca did not leave a written record,

but in the 1500s, Spanish began to interview some

of the descendants of the Inca

to write down these oral histories

and leave somewhat of a record of the Inca past.

An anthropologist was in Cusco,

poring over some of the records that were in the archives,

and came across a letter from 1568

that said that there was a royal palace.

- It outlines a court case

in which an Inca family was demanding the return

of their lands that included a mountaintop palace

that was named Picchu.

- Not only does it describe generally

where Machu Picchu is located,

but the Peruvian descendants who bring this claim

to the Spanish conquistadors claim themselves

to be descendants of Pachacuti.

- [Laurence] Suddenly, there's a brand new explanation

for this settlement in the sky.

[tense music]

- After he spent the first part

of his time as Inca king expanding the empire,

Pachacuti spent the second half

of his life building these royal retreats

that were on the outskirts of Cusco.

Many of these palaces are very similar architecturally

to what we see at Machu Picchu.

- [Laurence] Based on Spanish records,

many historians agree

that Pachacuti was probably involved

in Machu Picchu's construction.

- The Inca royalty itself was divided

into a series of royal lineages.

Each of them had royal estates.

It's possible Pachacuti's descendants

would spend time in Machu Picchu, probably relaxing.

- Machu Picchu was at a elevation of 8,000 feet.

That's 3,200 feet lower than the elevation of Cusco.

So during the nights, it was much warmer

and it was a much more pleasant atmosphere

in the middle of winter.

- If we look at Machu Picchu as a palatial residence,

the layout makes sense.

There are clearly sectors that are the most private,

the largest and most elaborate rooms.

- There's one dwelling at Machu Picchu believed

to have been the residence of the Emperor Pachacuti.

That residence is the only one that had its own bathroom

with flowing water through it.

- [Laurence] A reexamination of Machu Picchu's dead

reveals new information about who else lived here.

- They're just buried in the ground

and though they have objects,

they seem like everyday wares.

- The lack of treasures indicates

that these bodies were not necessarily royalty,

but they also don't have the same kind of injuries

and arthritis that would indicate

that they were laborers either.

- Those graves that Bingham dug

are really the servants and staff of the city.

- [Laurence] A technique called isotopic analysis tells us

even more about Machu Picchu's residents.

- Archeologists can take a small sample of bone

and vaporize it, essentially,

examining the DNA for traces of the diet

of the person while they lived.

And they found that these individuals ate a lot of corn.

- Corn was, in fact, a symbol of status among the Inca.

And what they find is these people ate mainly corn

because of their privileged status

as retainers and servants of royalty.

- [Laurence] There are more clues to be found

by studying the skulls.

- Some of the skulls that were found were very bizarre

and they didn't even look human.

- Some of the skulls have cranial deformation

and seem to be squished to a higher point at the top.

- It's really well known in the history of the Andes

that the people would bind their heads into different shapes

that had to do with an ethnic identity.

This was often done when an individual was born

and their head was very malleable.

- [Laurence] Modified skulls are not the only clues

that Machu Picchu was a royal hub.

- From the ceramics that were left in the burials,

they could determine this was a real heterogeneous

accumulation of people throughout the empire

who were actually at Machu Picchu working

as metallurgists, attendants, and staff.

- [Laurence] Leading researchers suspect Machu Picchu

was a place for Pachacuti

to entertain a vast array of guests.

- We can think of it as a 16th-century Camp David.

In addition to the varied visitors

that may have come to the site,

there were people that had to work there

to grow the crops, tend to the fields, to cook the food,

to make the crafts and the goods that were used.

So these discoveries have led to the idea

that this could have been a royal retreat

where people were coming from a variety

of different locations from around the empire.

- [Laurence] Many scholars speculate

that Machu Picchu was built in the mid-15th century

as a winter getaway for Inca Emperor Pachacuti

and his entourage.

But could the site have a more serious purpose?

- If political entertainment

and relaxation are the primary activities

that are being done at Machu Picchu,

then why all of these spaces that seem to be devoted

to religious ceremonies?

- Parts of the architecture

and the landscape where the site was built really suggest

that there is a sacred purpose behind Machu Picchu,

which is really significant when we think

about Inca worldview

and how they worshiped both their ancestors and the gods.

[tense music]

- In terms of the way in which the Inca worshiped,

we can't be entirely sure,

but we do know that they worshiped a number of gods.

[thunder rumbles]

- Illapa's the god of thunder, god of the weather,

god of rain.

Beneath that, it was a vast assortment of gods

and a host of spirits.

- Viracocha was the creator god

and one of the most prominent and important,

but Inti, the sun, was also very important to the Inca.

- During his first visit,

Bingham came across this curved wall

that caught his attention.

He famously called it the Torreon,

right, the turret or tower.

It really resembles the Temple of the Sun found in Cusco,

which has led scholars to believe

that this was another Temple of the Sun.

- Hiram Bingham was fascinated by this,

not only because of the rare curved architecture on top,

but it was built on top of a cave

that had itself very intricately carved stone.

- It's also very close

to what we believe to be the king's quarters.

There were places where it was the king's obligation

to honor and remember the deeds of Viracocha.

So he, as the son of the sun,

was probably stationed quite close to the Temple of the Sun.

- [Laurence] But the Inca didn't just worship gods

in the sky, they also worshiped water.

- The Inca are world renowned

as some of the most amazing hydraulic engineers

the ancient world ever knew,

and Machu Picchu is an incredible showcase

of their abilities.

- Not only did the Incan people believe

that it was access to water that gave you power,

but also that their ability to control that flow of water

was something that was given to them by the gods.

- For the Inca, everything is alive.

Pachamama, or Mother Earth, was very important

to this Inca spirituality.

And Pachamama had to be nourished through

different kinds of water rituals.

- [Laurence] Archeological studies suggest

that a site on the perimeter

of Machu Picchu called Chachabamba

was built specifically for the worship of water.

- Chachabamba was discovered in 1940,

a series of 14 sacred baths

that are believed to be a very key part

of their ceremonial services.

- Recently, some researchers went in

and did drone LIDAR work,

using lasers to map the ground,

and then you can remove that canopy of trees

and see what's below it.

And they were able to see

that there were a lot more conduits

that were diverting water from waterfalls

that were further away.

- [Laurence] But why here,

just two miles down the road from Machu Picchu?

- Some archeologists believe that Chachabamba

was a place where a traveler would stop to purify their body

and their soul on their way to Machu Picchu.

In 2009, a theory emerged that Machu Picchu

was, in fact, a destination for a spiritual pilgrimage,

a way to celebrate their origin story.

- The creator deity Viracocha called up the sun

and the moon first from the Island of the Sun

in Lake Titicaca.

He then used clay from the sides of the lake

and created the first people,

and they take the journey to establish Cusco

as the capital of the Inca Empire.

- The idea is that the baths

of Chachabamba are like Lake Titicaca.

One immersed themselves in this water.

Then the two-mile walk up to Machu Picchu represents

this walk across the land.

- If Machu Picchu was indeed a pilgrimage site,

we can picture people approaching the city

and conducting cleansing rituals

in places like Chachabamba and other sites.

- [Laurence] Pilgrimage or not, scholars believe

that many of the structures within Machu Picchu

served a religious function.

Among them, the Temple of the Three Windows.

- When Viracocha sends the people to Cusco,

he sends them in a cave entrance near Lake Titicaca.

And there are three cave exits,

so three windows symbolizing those three exits.

- [Laurence] Another feature of Machu Picchu

seemingly built for religious use

is the Temple of the Condor.

(condor shrieks]

- The condor was a sacred creature among the Inca.

They thought that the mountain gods could transform

themselves into condors and vice versa.

So not surprisingly, at Machu Picchu,

there's this big temple,

and they actually carved out of the bedrock

two wing-like structures and the head of a condor.

That's a place where they could offer sacrifices.

- [Laurence] Some of those sacrifices may have been animal.

- Some archeologists believe

that the Temple of the Condor was used

for sacrificing guinea pigs and llamas

as a symbol of power and fertility.

- [Laurence] And some offerings may have been human.

- There's a specific Inca ceremony called the Capacocha,

and it's very well known that young children were chosen

to be sacrificial victims when there were times of trouble.

- That seems very barbaric from Western society,

but if you are in an environment where you believe

that the gods need your sacrifices,

children are the absolute most precious thing

we could sacrifice.

- Machu Picchu may have been the place

for the ultimate sacrifice.

- Because the Incas were dependent upon all

of these spirits and gods around them,

it was very important

to maintain a good relationship with them.

And the way they felt they could best do that was

to offer offerings to them on a regular basis.

- We see this in various parts of the empire.

Children that were sacrificed have been found,

but there's no evidence of the Capacocha ceremony ever

to have took place at Machu Picchu.

We have not found any remains that relate to that.

- But you really can't deny that there would've been

some religious and spiritual use for these buildings

when the population itself was so tied

to their spiritual recognition

of these places and these entities.

to their spiritual recogn thany

since Hiram Bingham introduced Machu Picchu to the world,

and even after decades of scrutiny,

the site is reluctant to give up its secrets.

But the Inca did leave clues behind,

including ones that suggest

the site filled a very practical purpose.

- The Inca really had a phenomenal understanding

of the movement of the celestial bodies.

They were very spiritual

and they very much revered the sun and the moon.

- Incas obviously didn't have clocks and watches,

so they used passage of the sun

to determine their clock, so to speak.

The rocks themselves were like little sundials

so they could tell by the shadows on the rocks

what time of year it was, what time of day it was.

- Tracking the movement of the sun is very difficult

in itself, but they accomplish this with a lot of precision.

So the Temple of the Sun especially noteworthy

because, although it might seem

that it's just a beam of light projecting into the wall,

there's much more to it.

- The architecture reflects and encompasses

how they could have had such a precise understanding

of the movements of the cosmos.

[tense music]

- [Laurence] The Temple of the Sun

isn't the only building in Machu Picchu

that marks the sun's movement.

- There's at least two observatories in Machu Picchu.

One marking the summer solstice,

the other one, the winter solstice.

Beneath the Sun Temple, there's this cavity there

and is exquisitely cut stones, like stairways.

And the name of that carved area underneath the Sun Temple

is called Intimachay, which means cave of the sun.

- The sun enters the cave in June

for a certain window of time.

And in 2012, there was a team of researchers

that went and mapped the inside of this cave using LIDAR

and 3D technologies to really understand the details

inside the cave.

- [Laurence] They discover that this structure

is even more complex than it appears.

- The cave may not have only

had some of these solar alignments,

there's probably some lunar alignments as well

that show that there's much more in-depth understanding

of the movement of the heavenly bodies

than we may even understand

was actually happening at the site.

- [Laurence] While the Intimachay acts

like a solar calendar underground,

another carving tracks the sun from above.

- One of the very prominent features of Machu Picchu is

you go up on this precipice there,

and there's a rock carved right out of bedrock

and it's called the Intihuatana, the Hitching Post of the Sun.

It marks the four points,

north, east, south, and west,

and also it's thought to mimic the nearby sacred mountain

of Huayna Picchu,

which is the famous backdrop of Machu Picchu

because it models the shading of that mountain there.

- So the Intihuatana is this extraordinary measuring device.

And during the equinoxes when the sun is right above it,

it projects no shadow at all.

- It was a place for the Inca priests

to watch the equinox and the solstice,

and they would then ceremoniously tie the sun

to the hitching post

so that it didn't go farther north or south.

- [Laurence] Keeping time by observing the skies

was critical to the Inca.

- The way they're tracking the winter solstice

and the summer solstice

through these buildings becomes extremely important

for the planting and harvesting season.

- The Inca spirituality really was so much about nature,

so being in this location that's high up in the clouds,

you are really immersed in this environment of the gods.

You're close to that celestial movement,

which is so important to the understanding

of when to perform certain ceremonies,

when to harvest plants.

- Without being able to so accurately predict the seasons,

it would've been virtually impossible

for their terraced gardens to have been able

to support the people that were living there.

- So a variety of different kinds of architecture

at the site may have been used for astronomical observations.

- People might think of the Incas

as being a primitive culture,

but they created the largest empire in the New World.

However, on the other hand,

we'll probably never know the extent of Inca cosmology.

- It leaves us absolutely mystified

as to how they could have made these calculations.

How did they develop such an accurate understanding

of time and space?

- [Laurence] Whatever the driving force was

behind Machu Picchu's construction,

it's a testament to the ancient Inca's sophistication

as builders, engineers, and even astronomers.

But not everyone thinks the Inca created this place alone.

- In the 1960s, theories emerged regarding a lot

of structures around the Earth,

Stonehenge, Easter Island, the pyramids,

that suggested that it was impossible for human beings

to have created these architectural feats.

- When you look at a wall on Easter Island called Vinapu,

this building technique is identical

to what you see in Peru.

Perfectly-fitted granite blocks,

would seem they're using power tools

to cut very hard rocks, granite and basalt.

- It was believed that

for human beings to construct anything like this,

we would've had to have been aided

by a far more advanced technology

than was available on Earth at the time.

And according to proponents of the ancient astronaut theory,

we got help from other worlds.

[tense music]

- [Laurence] It may sound like the plot of a sci-fi movie,

but there are some things about Machu Picchu's construction

that defy logic.

- A few stones in the center of Machu Picchu

are over 50 tons.

And you look at these single stones

and see how perfectly they're fit,

there's not a good explanation, to this day,

how people with rudimentary technologies

were able to do that.

It seems impossible.

- The feet of engineering does seem otherworldly at times,

because even though the ashlar technique

was used throughout the Incan Empire,

which was a way that the stones were carved

and they fit together in a sort of puzzle piece,

how do you do it at the top of a mountain?

A closer examination

of the foundations underneath Machu Picchu show

such a significantly different architectural style

that it's possible that the foundations were built

by an entirely different civilization.

- Whether it's extraterrestrials

or some other sophisticated civilization,

who can do these things

and perfectly fit giant blocks of stone together?

- The ancient astronaut theory is considered by many

to be pseudoscience.

However, there is new evidence

that the history of Machu Picchu may be much, much older

than anyone has anticipated.

- There's a long history of civilization in the Andes,

going back to the first cities being built, 3000 BCE,

throughout what eventually became the Inca Empire.

- Some of these carved rocks are as big as box cars,

and archeologists believe that they predate the Incans

by hundreds of years.

- [Laurence] Just a short walk from the center

of Machu Picchu in an area named after Pachamama,

the Earth Mother, stands a large granite outcrop

that's been hiding a secret for over 1,000 years.

- In 2016, one of the Machu Picchu archeologists

discovered a faint symbol that raised some new questions.

- What's found on that panel is a man, a llama,

and some black-and-white geometric shapes.

Some people think that it's an indicator

that there's a much more ancient history

to Machu Picchu we're unaware of.

- Whatever it means,

it has no specific ties to the Incan population

in the 15th or 16th centuries.

- [Laurence] Further exploration of Pachamama

reveals even more puzzling cave paintings,

estimated to have been made as early as 800 AD.

- Perhaps the greatest indication

that there was some association

with ancient aliens comes from the Incan religion itself.

- [Laurence] And there's one Inca legend in particular

that can certainly be interpreted as supernatural.

- There's a legend that the Emperor Pachacuti,

on the eve of a great battle,

went to a lake and is reflecting on what to do next.

And that in this moment, a disc fell from the sky

from which emerged a face.

And the supernatural creature tells Pachachuti

that he's going to win the upcoming battle and many more.

The story is then that these huge monolithic stones

come to life and assist Pachacuti in his battle.

And these levitating rocks

are what helped build Machu Picchu in the first place.

There is no evidence to support any of these stories,

but there are many stories that indicate that the skies

above Machu Picchu today still remain a hotspot

for paranormal activity.

- UFO activity in Peru is quite considerable.

And, in fact, when you're in Peru,

the subject of UFOs is a very common one.

Most people do not doubt the existence

of extraterrestrial sky gods

who had the technology to fly through the sky,

to levitate stones and magically move them.

Is it possible that these same sky gods are the ones

who built Machu Picchu?

It's a common belief there that that is what was happening.

[tense music]

- [Laurence] Nearly 600 years after Machu Picchu was founded,

research teams aren't certain

how Machu Picchu was made, or why.

- It's estimated that potentially up to 60%

of the construction of Machu Picchu is underground,

and these deep foundations were necessary

to help with seismic movements and terrace drainage,

to make sure things would filter properly.

- To keep a place like Machu Picchu securely

on the mountaintop,

it takes under-the-earth infrastructure.

It's entirely possible

that there are subterranean chambers we've yet to contact.

In 2010, an engineer named David Crespy

came to Machu Picchu, looking specifically at those caves

under the Temple of the Three Windows,

and said that structurally, the wall that was in the back

looked like it might be hiding

an entrance into deeper chambers.

- He immediately alerts the other archeological teams

to his discovery, but gets no response.

After enough time goes by,

he reaches out to a French archeologist named Thierry Jamin

to see if he can help see what might be underground.

- [Laurence] Jamin gets approval to search the area

with ground-penetrating radar.

In April 2012, along with a team of archeologists,

he makes a stunning discovery.

- They did some geophysical investigations at the site.

And what he thinks he found

is some kind of a chamber below this door

that may have had a staircase leading into it.

- The radar also indicates a huge amount

of metal down there,

which could indicate silver and gold,

exactly the kind of riches that one would expect

to be buried with royalty.

[tense music]

- [Laurence] Like the ancient Egyptians,

the Incas mummified their great leaders,

not to memorialize their power, but to preserve it.

- They were not fancy burials, and they believed

that their ancestors did not die when they died.

They would go into the afterworld, but their spirit

would remain and would look over their descendants.

- In the chronicles that the Spanish left behind,

they describe instances of them eating

and drinking with these remains,

even building vast palaces as if they were still alive.

So the Spanish Conquistadors were horrified

with the amount of power

that these mummies had over the living.

Maybe this whole place was dedicated to the afterlife.

Hiram Bingham's crew is believed

to have excavated all of the graves on Machu Picchu,

but they perhaps missed the most important one.

- [Laurence] The Peruvian government

denies Jamin's request to excavate further,

but he has a hunch about what or who

may be lying within the chamber.

- Thierry Jamin believes that Pachacuti,

who is one of the legendary builders of Machu Picchu,

would be buried there too.

And his gold mummy was somehow interred inside this wall.

- It's possible that Pachacuti's mummified remains

were once located in the cave

underneath the Temple of the Sun

that Bingham had originally believed was a burial chamber.

- [Laurence] Pachacuti dies in 1471.

According to his wishes,

the whole of the Inca Empire mourns for a year

and then spends a month celebrating his life.

- Although his remains were originally installed

in the capital city of Cusco,

according to the Spanish chronicles,

a person of his stature

would have made regular outings, even as a mummy.

- [Laurence] But after the Spanish conquest

starting in 1532,

just when his people need him most,

Pachacuti's mummy mysteriously disappears.

- In 1559, a Spanish magistrate claims

to have collected, by order of the viceroy,

the deceased bodies of Inca kings and queens,

and then shipped them to Lima.

The bodies were deposited in a hospital

in the city of Lima,

and they were eventually buried there

where we believe they can still be found.

- [Laurence] None of those human remains

have been positively identified as Pachacuti.

- Unofficially, the question remains

were Pachacuti's mummified remains

instead brought to Machu Picchu for reburial?

Is Machu Picchu a location for the life and afterlife

of the Inca's greatest leader?

- [Laurence] Thierry Jamin and his crew are keen to know

if what they've seen on that radar

could really be Pachacuti's tomb.

For now, the truth is staying buried.

- Today, we can't help

but look at Machu Picchu through our Western eyes.

But, of course, it was made by people

who had a very different cosmovision than we do.

Part of the mystery of Machu Picchu is we just don't know

how to look at it the right way.

- Whether Machu Picchu was built for war or peace,

as a place of worship or a place to unwind,

an astronomical wonder or a tomb for the dead,

the search for more answers

about this astonishing site continues.

As top archeologists employ new technologies,

perhaps they will one day decipher the true purpose

of Machu Picchu.

I'm Laurence Fishburne.

Thank you for watching "History's Greatest Mysteries."

[mysterious music]