Original subtitles

Tonight, one of the world's most famous landmarks.

Stonehenge is an amazing place.

SAMI JARROUSH: These stones are enormous.

Some of the biggest ones rise up 30 feet

and weigh an estimated 25 tons.

To this day, no one knows how it was built or why.

CAROLINE CORY: Were people really that much smarter than us

5,000 years ago?

Now, we'll explore the top theories

surrounding this mysterious monument.

It's everything from a magical feat

by King Arthur's wizard, Merlin,

to a Druid venue for human sacrifice.

MICHAEL DENNIN: Experts have found two skulls

that show evidence of primitive surgery.

This was a place that was specifically built for the dead.

Can modern technology unlock its many secrets?

Now, suddenly this opens up a whole new world of theories

which could actually be true.

What is the true purpose of Stonehenge?

[music]

Salisbury Plain, England, 2021.

While traveling the UK, researcher Michael Goff

visits one of the country's most famous landmarks.

SAMI: Like millions before him, he goes to see Stonehenge,

the massive, mysterious circle

of giant stones that draws

as many as 9,000 visitors a day.

MARC ARONSON: Stonehenge is like a letter from the deep past.

It's there, it's physical,

you can't ignore it.

But what does it mean?

LAURENCE: Goff believes he's finally solved the mystery,

one that begins hundreds of years ago.

The first written mention of Stonehenge

is not until 1130

by Archdeacon Henry of Huntington.

MICHELLE KOONS: He describes the monument,

but he doesn't actually guess

on what it may have been for.

LAURENCE: But soon after, someone else does.

In 1136, a British cleric named Geoffrey of Monmouth

shares the first documented theory on Stonehenge

in his book "The Histories of the Kings of Britain."

Monmouth tells of a time in the fifth century

when the Saxons are ravaging the land.

Treacherous Saxon leader Hengist

masterminds the betrayal and murder

of more than 400 British nobles,

leaving a mass grave in Salisbury Plain.

MICHELLE: The high king Ambrosius Aurelianus

asks his people to create a monument to the dead.

But no one feels worthy of this task,

so he was told to ask the wizard Merlin.

LAURENCE: According to Geoffrey of Monmouth,

it's this legendary wizard

who brings the famous stone circle to England.

Yes, we are talking about that Merlin,

the famous wizard from the Arthurian legend.

Merlin is the one who tells Aurelianus

that in order to bless this burial site forever,

he needs to build a stone circle.

Merlin doesn't want to build one from scratch,

he wants to steal an existing one from Ireland.

SAMI: Merlin says these particular stones in Ireland

have healing properties as well as a kind of magic

that will preserve the memory of the dead.

LAURENCE: According to Monmouth's book,

Aurelianus and Merlin bring a small army to Ireland

to capture the stones.

15,000 men tried to bring the stones from Ireland,

but they couldn't.

LAURENCE: Legend has it that Merlin flies through the air

to capture the stones,

then sets them up on Salisbury Plain.

Monmouth writes that Ambrosius is eventually buried there

along with his brother, Uther Pendragon,

father of King Arthur.

This really seems like a fantastical theory,

especially because we know that Merlin and King Arthur

were fictional characters.

But this theory persists for hundreds of years

as the explanation of Stonehenge.

LAURENCE: Then in the 1620s,

English architect Inigo Jones

uses new tools to analyze the site.

So, now it's the Renaissance,

and people are less interested in magic

and more interested in science.

King James I sends Jones out to Stonehenge

to do a proper survey with the modern equipment of the day.

What Jones does, is he looks

at the site from the perspective

of a builder's eye,

being an architect.

MICHELLE: So, Jones goes out to the site

with his student, John Webb,

and he sees many similarities

in the architecture of Stonehenge

to what we see in Roman architecture.

And he becomes certain that's who built it,

which means it's much older than Monmouth's estimate

of the fourth century A.D.

BRANDON CLIFFORD: And in some ways this makes sense,

because the Romans

had conquered the British Isles

in 50 B.C.,

and just some 100 years later,

they were treating it as a colony of Rome.

SAMI: But unlike aqueducts, and roads, and amphitheaters,

there is no obvious utility to Stonehenge.

So, Jones and Webb study ancient Roman architectural plans

to try to understand what this could be for.

MICHELL: So, they look for any Roman architectural plans

that might be similar to Stonehenge.

They find two in a book from about 30 B.C.

called "De Architectura."

One of these is called the monopteros,

and the other is the peripteros,

and they're both Roman temples.

LAURENCE: Jones and Webb are convinced

they know what Stonehenge is.

In 1644, the researchers go a step further

to prove their theory.

Jones creates a draft of a restoration

of what he thinks the monument of Stonehenge

would have looked like before it fell into ruins.

According to Jones' drawing, Stonehenge was laid out

in a precise Roman form

based on four equilateral triangles

arranged to create a hexagon

surrounded by a circular colonnade.

JIM: Stonehenge resembles the layout and proportions

of Vitruvius' designs,

but because it was built without a roof or enclosure,

Jones concluded that it was built

to worship the sky god Caelus.

BRANDON: Even the people of the time

were having trouble justifying Jones' idea

that this was a Roman construction,

because you can look at Roman construction

and understand it through its refinement

and its pure geometric expression.

Contrast that against Stonehenge's megalithic

trilithon assemblies, even at the time,

it was understood that this was a far-fetched idea.

LAURENCE: Meanwhile, around the same time,

renowned English archaeologist John Aubrey

is in the midst of his own excavation at Stonehenge.

Aubrey makes a lot of discoveries at this site,

and one of these was a ring of pits,

56 of them around the outside of the main monument,

and these are now known as the Aubrey holes.

Curiously, these holes were dug and filled many times over.

MICHAEL: On a hunch, he does something

no one has ever done before.

He sketches out the positions of the stones

and then compares them to the stars.

He realizes something really important,

that these stones are placed so precisely,

that on the summer solstice, the rising sun

appears precisely between the two largest stones.

LAURENCE: To Aubrey, this can't be a coincidence.

Aubrey spends over 20 years analyzing Stonehenge,

and publishes his findings in 1666.

Like Jones and Webb, he agrees that Stonehenge is a temple.

But he thinks it predates the Roman arrival in Britain

by a great deal, and was instead built

by the Druids.

MICHAEL: The Druids themselves were active in early Britain

in the third century B.C.

They're an early mysterious group of priests

that were part of the Celtic religion.

Druidic law forbade writing down religious teachings,

so we don't really know much about them today.

SAMI: Greek and Roman writers, including Julius Caesar,

judge the Druids to be extremely knowledgeable,

especially in the fields of mathematics,

astronomy, and science--

all subjects that would be useful

in planning and constructing a massive stone monument

aligned to the sun.

LAURENCE: Over the next 100 years,

additional British scholars advance Aubrey's research,

including 18th century scientist William Stukeley.

Stukeley really spends a lot of time

studying the ancient writings

focusing on the Druids' ancient religious beliefs.

It was thought that the Druids worshipped the sun,

held very elaborate ceremonies,

and they potentially even included human sacrifice.

If that is the case, Stukeley proposed

that they would need a venue for these practices,

and Stonehenge is that venue.

SAMI: In fact, one stone in particular

even becomes known as the "slaughter stone,"

because the hollows of the stone turn red

when they fill with rainwater, which some believe to be stains

from the blood of the victims of human sacrifice killed there.

LAURENCE: Stukeley is also one of the first

to try to precisely date the monument.

BRANDON: So, based on the construction methods,

and the layout, and the alignments at that time

with the summer solstice,

Stukeley believes that it was constructed

in about 460 B.C.

And for the next 100-plus years,

this is the final word on Stonehenge--

it's a Druid monument from somewhere around 400-500 B.C.

Case closed.

MICHAEL: This theory is so pervasive

that many people today still believe

it was built by the Druids and used for their ceremonies.

SAMI: But those people are wrong,

because a new scientist is about to uncover evidence

that Stonehenge is much, much older

than we ever believed.

LAURENCE: For hundreds of years, scientists and visitors

have wondered about the true purpose of Stonehenge.

SAMI: It's everything from a magical feat

by King Arthur's wizard Merlin,

to a Roman ruin,

to a Druid venue

for human sacrifice.

MICHELLE: These diverse theories definitely show

that people have been interested

and curious about Stonehenge

for a very long time.

LAURENCE: Then, in the late 1700s,

an archaeologist named William Cunnington

proposes a new theory,

one that starts with an accident.

In 1797, a large tremor is felt by the villagers

in Cunnington's home town of Wiltshire, England.

Shockingly, the cause

of this tremor is actually

some of the massive stones at Stonehenge falling over.

LAURENCE: The impact can be heard and felt

at least half a mile from the site.

SAMI: Sometimes known as the Great Fall,

this is one of only three times

that stones have collapsed at the site in modern times.

One of the stones actually breaks as it hits the ground.

The fall of any of these stones is really a sad occurrence,

but to lose three of the largest stones at Stonehenge

was really quite devastating,

considering they have stood there for thousands of years.

For Cunnington, this was not only a tragedy,

but it was an opportunity,

because it meant that he could start to dig

in the place where the stones previously existed.

LAURENCE: By 1802, Cunnington digs a pit

that's six feet deep.

BRANDON: And in this pit, he uncovers animal bones,

charred wood, and antler bones that were used for digging.

LAURENCE: His early finds generate excitement.

SAMI: In 1804, nobleman and fellow archaeologist

Sir Richard Colt Hoare begins financing

Cunnington's excavations, enabling him

to do the kind of detailed work that he wants.

This is perhaps the first serious and sustained attempt

to understand what Stonehenge truly is.

MARC: Cunnington figured out that Stonehenge

actually had two different kinds of stone.

The large stones are what's called sarsen, or sandstone.

And there are a set

of smaller standing stones

which are called bluestone,

which are a variety of kinds of stone

which when wet can seem bluish.

SAMI: Because there are two different kinds of stone

in the circle, he believes

that there are probably two different periods

of activity here,

but he can't conclude much more than that.

MICHELLE: For seven years, the pair

conduct many excavations and investigations on the site,

and they discover areas where there are burial mounds,

and in these mounds, there are human remains.

LAURENCE: This startling discovery

only opens up more questions.

SAMI: So, like the many who've come before him,

Cunnington feels that without written records,

he's at a loss.

LAURENCE: After ten years, in 1807,

Cunnington finally gives up.

MICHAEL: Though Cunnington and Hoare actually reach a dead-end,

they end up excavating 465 sites at Stonehenge,

and their archaeological studies

are what inspires the next generation.

LAURENCE: Including a researcher named John Lubbock,

who picks up the mantle in 1862.

Lubbock comes in and studies the excavations

of Cunnington and Hoare,

ultimately focusing on these burial mounds.

BRANDON: For Lubbock, the burial mounds

are likely the key to unlock the mystery of Stonehenge.

SAMI: Lubbock spends over three decades

investigating Stonehenge,

and eventually he makes a surprising breakthrough.

He's able to determine that along with the bones

and bone fragments, there are cremated remains.

LAURENCE: According to Lubbock, this means Stonehenge

is much older than anyone has ever considered.

By this time, archaeologists had realized

that cremation hadn't been practiced by the local Britons

since the Bronze Age,

which dates back to about 3000 B.C.

MICHAEL: Lubbock finds proof that Bronze Age tools

were used to carve the stone and then bury it

alongside the cremated remains of the artisans.

Up until this point, the monument is believed

to be no older than the fifth century B.C.

Lubbock's claim places it 2,500 years older than that.

The Bronze Age is way, way, way before the Druids,

the Romans, and the legends of King Arthur.

There are two ways

that you can feel about these new revelations.

First, the bad news.

I'm sorry, but yes, we're back at square one

when it comes to theories on Stonehenge

and what it was for.

Every previous theory is now officially wrong.

But the good news-- now, suddenly this opens up

a whole new world of theories which could actually be true.

Unfortunately, progress after that isn't immediate.

It's not for another 100 years after Lubbock

that we get our next breakthrough.

LAURENCE: In 1961, a new research team

led by Boston University astronomer Gerald Hawkins

descends on Stonehenge with state-of-the-art technology.

SAMI: Hawkins and his team map out every stone

and every pit at the site,

and they also collect astronomical data,

plotting out the stars each day that they're there.

They punch the coordinates of all those things onto cards

and feed them into a huge IBM 704 mainframe computer

at Boston University.

MICHAEL: Hawkins is shocked to discover over 100 alignments

between the stones, and the sun, moon, and stars.

In the 17th century, Aubrey thought the stones

might have tracked the sun one day a year.

Hawkins thinks it does way more than that.

SAMI: Based on these alignments,

Hawkins decides that the monument

can track the sun and moon over a recurring 56-day cycle,

as well as possible eclipses.

Remember when Aubrey found those 56 small pits

in a circle around the stones?

Hawkins believes that those once held smaller stone

or wooden markers that would be moved

around the circle to track the moon's phases.

LAURENCE: Hawkins publishes his findings

in the 1965 book "Stonehenge Decoded."

When Hawkins eventually publishes his works,

it's a bestseller.

I mean, this book is rewriting

what we understand from prehistory.

But in doing so, he's getting quite a bit of backlash

from his contemporary archaeologists at the same time.

SAMI: In fact, one of Britain's top archaeologists,

Richard Atkinson, is scandalized by the idea.

He believes Stonehenge was built

by, quote, "howling barbarians"

who couldn't possibly have had the sophistication

to make astronomical calculations.

LAURENCE: Hawkins is ridiculed until 1971,

when Oxford professor Alexander Thom

finally backs up his theory.

Alexander Thom studies

many stone circles throughout Britain.

He had already studied over 250.

This includes Stonehenge, and some that are even older.

Thom decides that all of these sites

had astronomical use, and that 4,000 years ago,

people had this very sophisticated knowledge

of engineering, and linking their stone circles

with the skies.

SAMI: Far from howling barbarians

or mindless savages, Thom believes

that the creators of Stonehenge use the huge stones

in conjunction with the landmarks on the horizon

to mark the position where the moon rises or sets.

Thom finds their calculations to be incredibly precise,

close to what modern astronomers can do with tools and technology

that would have been unthinkable 5,000 years ago.

We have computers and the Webb Telescope.

They had antlers to dig with and very large stones.

It's incredible.

MICHELLE: But there are many scholars,

archaeologists who just don't really agree.

As enigmatic and interesting as this theory is,

it still doesn't explain

why there are so many human remains

in and around the monument.

So, there has to be even more to this place.

LAURENCE: In early 1971, Oxford engineer Alexander Thom

announces a compelling new theory.

Like other ancient stone circles,

Stonehenge was built to track the movement of the heavens.

But this doesn't take into account one critical fact.

Building this structure is so dangerous,

it seems inevitable that workers

would die, and for a long time,

this is the primary theory as to why human remains

are found at the site.

MICHELLE: One of the things that people always talk about

is just how difficult

it would have been to move

these large stones.

And we can start with the sarsen stones,

the sandstones.

The closest place they could be from

is Marlborough Downs, which is over 20 miles away.

SAMI: Now, to you and I,

20 miles might not sound that far.

But these folks had no cars.

We don't think they had

wheeled carts, either,

or any large beasts

that could pull them.

And these stones weigh an average of 25 tons.

The largest stone of all weighs 45 tons.

That's as much as an adult humpback whale,

and that's just one stone.

LAURENCE: So, how did they move them?

MICHAEL: Some believe the ancients used wooden sleds.

Others postulated that they used wooden rollers

made from tree trunks.

Those are just the sarsen stones.

The other stones, the bluestones,

there's nothing like them

anywhere remotely close to the site.

The best estimate we have is that these stones

come from Wales in the Preseli Mountains,

which are 140 miles away.

We're talking a vast distance for ancient technology.

LAURENCE: After the haul, the work is far from over.

At the site, the stones have to be shaped

with very simple bronze tools, chipping off small pieces

to taper the stones as needed.

Then, to fit the upright stones with the lintels, the builders

had to use an intricate tongue-and-groove system

that was used predominantly in wood.

And then, using antler picks

and stone tools,

they had to dig out the cavity

in which the stones could be placed

so that they would stand tall and not fall.

LAURENCE: Researchers estimate that it takes

more than 10 million combined man hours of labor

to construct the monument.

MICHELLE: This would be equivalent to 1,200 people

working nonstop, 24 hours a day,

for an entire year.

LAURENCE: For almost a century, the bodies found at Stonehenge

are believed to belong to the dedicated workforce.

But in 2008, British archaeologist

Michael Parker Pearson makes an astonishing discovery

that suggests something different.

MICHELLE: Michael Parker Pearson is the head

of the Stonehenge Riverside Project,

and he goes through and studies the human remains

found at the site.

SAMI: Interestingly enough, he discovers something

that nobody else has realized before.

There are not just male workers' bodies

buried on the site.

There are also women and children.

Suddenly, we now realize that the burials

probably aren't just from construction accidents.

This was a place that was specifically built

for the dead.

LAURENCE: To figure out how old the remains are,

Parker Pearson uses cutting-edge radiocarbon dating.

MARC: He learns that they're not just from one period,

but they were deposited there in an over-500-year period.

LAURENCE: Next, Parker Pearson tries to figure out

who these people were.

Alongside one of the burials

is a mace that would have been

associated with a form of nobility at the time.

MICHAEL: Another burial mound contained a number

of bronze and copper knives, daggers,

and many of these had ornamental designs.

These fine objects actually provide the evidence

that it was the elites that were buried here at Stonehenge.

BRANDON: This isn't a mass burial site,

because over the course of about 500 years,

there are only 240 burials that took place.

LAURENCE: But where did these ancient nobles come from?

MICHELLE: While there's evidence that people

are buried at Stonehenge, there's no evidence that people

actually lived there full-time.

So, he looks at the nearest settlement

to figure out if there are more clues.

LAURENCE: Two miles north of Stonehenge

is an area known as Durrington Walls.

SAMI: Durrington Walls contains nearly 300 dwellings,

making it the largest village in northern Europe at the time.

And in the middle of it, Parker Pearson finds the remains

of a giant wooden henge-- Woodhenge, if you will.

Not only do Stonehenge and the wooden structure

look very similar, but radiocarbon dating

indicates that it was in use right around the same time

Stonehenge's largest stones get installed.

LAURENCE: Why would these two structures

be built so close together?

Parker Pearson believes it's because

they're spiritually linked.

MICHELLE: To him, Stonehenge

isn't just an isolated structure.

Parker Pearson believes that we're looking at a pairing--

one in timber to represent the transient nature of life,

and the other in stone to mark the eternity of death.

What he's suggesting is that Stonehenge

may represent the final resting place

both in body and in spirit of ancient peoples.

The two henges, wood and stone, represent this journey

both literally and figuratively.

So, perhaps if one were near the end of his or her life,

they would come to the wooden henge to die,

and then be buried at Stonehenge.

MICHELLE: We really don't have any way to know

if this is actually the case.

The ancient builders have left us with a mystery

that will probably never be solved.

In 2008, a pair of archaeologists

are granted rights to the first excavation

of Stonehenge's inner circle in almost five decades.

What they find suggests a whole new purpose

for the monument, one that brings visitors

from all over the world.

During their digs at Stonehenge,

Geoffrey Wainwright and Timothy Darvill

focus specifically on the monument's bluestones.

Darvill and Wainwright find

the actual quarry

of the bluestones in Wales,

and it's a site known as Carn Menyn.

SAMI: They spend six years

surveying the area,

trying to figure out why

the ancient people would have

transported these bluestones

all the way to Stonehenge.

What's so special about them?

One thing they discover is that

the stonecutters who managed

to remove the rocks

also dug manmade springs.

To see this type of manmade spring

in the ancient world

is extremely rare.

MICHELLE: Darvill and Wainwright suppose that this

is some kind of medicinal spring,

and that the bluestones

that were brought to Stonehenge

were brought there for healing purposes.

LAURENCE: Some of Stonehenge's earliest theorists

also believed in the site's healing properties.

SAMI: In 1215 A.D., the British poet Layamon

writes that the stones hold magical healing power.

According to him, the ancient people

would wash the stone, and with the water,

quote, "bathe away their sickness."

This sounds very much like what Darvill and Wainwright

had found in Wales.

MICHELLE: Perhaps these writers from the Middle Ages

had heard some world histories

that had been passed down for generations

that these stones held some healing powers.

LAURENCE: More evidence is uncovered

when they take a closer look at the human remains.

MICHAEL: They find an unusual number of skeletons in the area

with signs of disease or injury.

About half of them are from outside the vicinity.

In fact, isotope analysis of teeth from the remains

at Stonehenge find people had traveled

from as far away as Germany, Italy, and France.

Experts have even found two skulls

that show evidence of primitive surgery.

It could very well be that Stonehenge

was some kind of hospital.

LAURENCE: In 2013, another group of academics

expands on this theory.

SAMI: Researchers at England's Royal College of Art

make a strange request to the government.

They ask for permission to, quote, "whack the henge,"

with rounded quartz hammers.

MICHELLE: They suspect that the stones

have special acoustic or sonic healing properties.

SAMI: The government grants their request,

and the results are actually pretty cool.

'Cause when struck, each stone gives off

subtly different sounds and reverberations.

And the circular arrangement

enhances the sound quality and volume.

It's like you're sitting in a sound room, for the most part.

It's as if the stones are meant to be played.

MICHAEL: The rocks produce sounds that are so clear

that churches in the area use them as bells

well into the 1700s.

MICHELLE: One village nearby is actually named Maenclochog,

which means "ringing stones."

LAURENCE: But can sounds actually heal?

Many cultures think so.

Ancient Egyptians believed that sounds

can generate vibrations with healing abilities.

They even built structures

to amplify the therapeutic effects

of these beneficial sounds during religious ceremonies.

CAROLINE CORY: In ancient Greece it's widely believed

that diseases can be cured

with repetitive sounds.

Sound therapy plays a very important role

in Greek medicine.

MICHAEL: But of course, if Stonehenge

actually was a hospital, the sad thing is,

we only really know about the people who died there.

This makes it incredibly difficult

to understand or determine

how successful a hospital it actually was.

LAURENCE: For centuries, scholars have debated

why Stonehenge was built.

But equally as puzzling is how it was built.

SAMI: In 1968, Swiss author Erich Von Daniken

believes he has simultaneously

answered both of these questions.

And the answer is aliens.

Von Daniken claims it simply

makes no sense that

ancient people would have been

able to transport these stones on their own

and build these structures.

And the fact that we still

can't figure out how they did it

is pretty suspicious.

MICHAEL: It forces us to ask the question,

were people 5,000 years ago talented, smart enough,

and had the right ability to build something like this?

Von Daniken believes that aliens shared their technology

with humans to move human civilization forward

in the areas of science and technology.

He feels they did this at several times

in human history, and that explains

many different monuments and structures

all across the globe,

including the ancient Egyptian pyramids

and the Easter Island Moai structures.

CAROLINE: So, in the case of Stonehenge,

the aliens helped teach the humans about astronomy,

and then helped them move and arrange the stones

in this particular pattern.

This idea is picked up in a 2008 book,

"The Gods' Machines: From Stonehenge to Crop Circles,"

by author Wun Chok Bong.

He suggests Stonehenge had a dual purpose.

MICHAEL: He believes that the astronomical orientation

of the site was really an aid for navigation

so that aliens could figure out where to land.

CAROLINE: According to Wun, after a ship landed on top,

the stones could act as conduits for electricity

pulled out of the Earth.

So, the monument is actually a combination of landing pad

and charging station.

LAURENCE: In 2013, an unexpected source

offers proof of UFO activity in the area.

In June of 2013, the British Ministry of Defense

declassifies their final collection of UFO files

after closing the program down.

MICHAEL: One of these files includes several photos

sent to the ministry that show a disc-shaped object

hovering over Stonehenge.

LAURENCE: This is just one of many reports

of unexplained aerial phenomena at Stonehenge.

In 2019, Philippe Rosset is taking pictures

of the sunset in Knap Hill, 15 miles from Stonehenge,

and he spots a bright spherical object

on the horizon.

The ball of light is then joined by another,

and then several more.

The spheres appear to create some sort of formation.

They've hovering silently in the sky.

MICHAEL: In 2020, a couple driving in Mere, Wiltshire

observe a disc of light

hovering near Stonehenge.

WOMAN: Look at that thing in the sky.

MAN: Whoa.

WOMAN: What is it?

They capture it on video, and just as suddenly

as the disc of light appeared, it vanishes.

LAURENCE: But most modern scholars are skeptical.

MICHAEL: At the end of the day, is there anecdotal evidence

of UFO activity near Stonehenge?

Certainly. But is this evidence

that aliens built Stonehenge? Not really.

SAMI: Throughout history, people have wanted to believe

that humanity at the time of Stonehenge's construction

were savages or barbarians, but I think that's foolish.

Okay, physically, they were just like us--

maybe not the exact same DNA, but similar in most respects.

So, if you're insulting them,

ultimately, you're just insulting yourself.

LAURENCE: With each new discovery,

there's hope that we're one step closer

to figuring out what Stonehenge is

and why it was built.

SAMI: You think it's a cemetery,

but it also tracks the sun's position.

How does that detail fit in?

At this point, the more

we study Stonehenge,

in some ways, the less we know.

LAURENCE: But in 2021, Michael Goff believes

he may have finally solved the puzzle.

CAROLINE: When researcher Michael Goff is at Stonehenge,

he already knows about the monument's alignment

with the heavens, and he thinks

that was a purposeful choice.

But while he's looking around,

he realizes there's a lot more to it than that.

MICHELLE: Goff starts by studying how Stonehenge

would have looked thousands of years ago

before any of the stones

were lost to time.

SAMI: He reconstructs the entire site

and demonstrates that the monument's outer circle

originally consisted of 30 sarsen pillars

and the same number of connecting lintel stones.

MICHAEL: He also notes that the four cardinal points--

north, south, east, and west-- line up with the structure.

This means sunlight

is intentionally focused

through the stones,

casting light and shadows.

SAMI: This was all known before, along with the fact

that Stonehenge tracks the length of the year,

since the annual solstice

appears in the same spot every time.

LAURENCE: But Goff believes that with one extra tool,

Stonehenge could track more than just the time of year.

Goff figures out that if you add some smaller markers

in the middle, Stonehenge could tell the time of day every day,

like a sundial.

According to Goff, Stonehenge actually had moving parts

that are now missing.

These could have been little stones,

or maybe even pieces of wood

that have since been lost to time.

Some small stones have actually been found

within the monument that could have served this purpose.

The real trick to this, however, is that these stones or markers

would have had to have been moved every year

to keep the clock accurate.

LAURENCE: So, how did they know where to move them?

Goff believed they used a particular constellation,

the Southern Cross, that would appear

prominently right on the horizon in that area

thousands of years ago.

According to Goff, every year when the Cross

was centered in the southern gap at Stonehenge,

the people could just move the small stones

to calibrate their clock for the upcoming year.

LAURENCE: Around the same time, more evidence is uncovered

to support this, but in a different location

and by a different team.

MICHELLE: Archaeologist Michael Parker Pearson

goes to Wales with a team to excavate in the area

where the bluestones were found.

There, they find a dismantled stone circle

made from bluestones

at a place called Waun Mawn.

SAMI: Researchers start to wonder

if these Waun Mawn stones might be related

to the stones at Stonehenge.

MICHELLE: As they search for evidence

using modern-day scientific techniques,

they realize that these two circles

have the same diameter of 360 feet across,

and both are aligned to the midsummer solstice sunrise.

LAURENCE: But one small clue proves the connection

is much bigger.

There is evidence that Waun Mawn was dismantled,

most of its stones pulled up and removed.

But in one of the holes, a stone chip is left behind.

A computerized model is made of the chip,

and incredibly, that chip fits perfectly

into one of the stones at Stonehenge,

one that's called Stone 62.

It's like a key into a lock.

Parker Pearson concluded

that around 3000 B.C.,

most of the stone circle

at Waun Mawn was dismantled,

and the stones were carried

the some 140 miles to Stonehenge.

LAURENCE: But why go to such lengths

to excavate and arrange the huge bluestones,

only to then move them 140 miles away?

Goff believes his clock theory holds the answer.

Today, the Earth's tilt has changed so much

that the Southern Cross

is no longer visible at all from Stonehenge.

This slow movement was happening back then too.

Goff believes that's precisely the reason Stonehenge was moved.

MICHAEL: Goff's theory is that the ancient clock

was first installed at Waun Mawn,

because that's where the Southern Cross

is at the horizon, and you can use it as a clock.

As the Southern Cross disappeared from that location,

they moved it 140 miles away, rebuilt it at Stonehenge

where the Southern Cross is visible at the horizon,

and now you get another 100 years of use

out of your clock.

It's a pretty cool idea,

but you also have to ask yourself,

scientists and archaeologists

have been studying Stonehenge for centuries.

How could a clock not have been discovered before?

LAURENCE: According to Goff,

it's all because of the number 30.

SAMI: There are 30 pillars at Stonehenge,

and therefore the clock theory never worked

with our current 24-hour concept of time.

That's why nobody ever figured it out.

MICHAEL: Once you try it with a day that's broken up

into 30 parts-- so a 30-hour day--

Goff's theory works perfectly.

The total length of the day is the same.

It's just the hours are now 48 minutes long.

LAURENCE: But if Stonehenge is a clock,

why are human remains buried here?

The burials of the elite or royal people,

the clock doesn't seem to explain those,

until you think about the fact that maybe the timekeepers

are also the rulers of this society.

You can imagine that type of knowledge

would be quite powerful at this time.

So, the leaders would have lived, died,

and be buried with the source of their power, the clock.

MICHELLE: Look, there's a popular saying in science,

"correlation does not equal causation."

Just because your football team won

when you wore mismatched socks,

doesn't mean this is why they won.

And unfortunately, this applies to Goff's theory.

Just because it lines up,

doesn't mean this is why they did it.

SAMI: And just because there are bodies,

doesn't mean it's a cemetery.

You can apply this to pretty much every theory

about Stonehenge.

We'll never have any records that tell us what this thing is.

These ancient builders have left us with a mystery

that will probably never be solved.

Recent dating of charcoal

found at Stonehenge proves

the site has been in use

since 7000 B.C., long before

the stones ever arrived.

This exciting new evidence gives archaeologists

many more puzzles to solve.

I'm Laurence Fishburne.

Thank you for watching

"History's Greatest Mysteries."