NOVA

It's one of the world's most iconic prehistoric monuments.

Who built it and why

have inspired countless theories.

Was it an ancient cathedral or burial place?

Or even a Stone Age observatory or computer?

There's been so much written about Stonehenge.

Every generation has come up with new ideas,

some great insights, others rather nutty.

Now an archaeologist has recovered clues

about the people who raised these enigmatic stones

and what motivated this extraordinary feat

of prehistoric engineering.

Provocative new evidence reveals hidden secrets

of the people who built Stonehenge

and what happened to them.

5,000-year-old bones testify to the elite families,

perhaps a single dynasty, that ruled Stonehenge.

Groundbreaking new work is giving us intimate glimpses

into the builders' lives

and the beliefs that inspired this unique monument.

Now we know where they came from,

what they ate, and how they celebrated.

But what motivated them to haul some of the rocks here

from outcrops in Wales, 180 miles away?

And can these bones solve the ultimate mystery:

Why did the power of the Stonehenge people

finally fade

and their colossal monument fall into ruin?

Can science finally lay to rest the "Ghosts of Stonehenge"?

Right now, on

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The extraordinary story

of the lost builders of Stonehenge

begins almost a century ago.

A team led by archaeologist William Hawley

was digging at Britain's most famous prehistoric monument

when they uncovered an outer ring of pits.

Digging into them, they found burned fragments of human bones.

Hawley dug up lots of cremation burials at Stonehenge,

but he didn't know what to do with them,

so they were left with his assistant,

put into sandbags,

and his assistant buried them in 1935.

British archaeologist Mike Parker Pearson

was granted special permission to recover these remains.

Hawley's assistants had reburied all the bones in a single pit,

so Mike's team was unsure of what they might find.

I think we just have to very carefully

loosen the soil bit by bit.

This is desperately uncomfortable.

Yeah, it is, quite.

Yeah.

So we're just going to take it in turns

so long as each of us can stand.

Till the blood rushes to your head

and you start to feel faint.

That's already happened.

One clue was an entry in the assistants' notebook

that the remains had been reburied under a plaque.

Since we dug down into the pit,

we came to a layer with a lead plaque,

and Hawley's assistant had had it inscribed to say,

"Here are the bones of the people of Stonehenge."

Oh, crikey!

We don't see a lot of bone.

But what was beneath the plaque was a crushing disappointment.

I think we were all hoping that the two men

who buried these bones for posterity

would actually have put them in decent containers.

But all we're really looking at is very loose cremated bone.

I was hoping it was going to be easy,

but this is the worst-case scenario.

The remains from all the different pits

were hopelessly intermingled.

We were really hoping

that he was going to have put them all

individually within the pit,

but they were all mixed together.

We realized that we were looking

at a great mass of mixed-up material.

This was going to be a very long and difficult job,

to disentangle all the different fragments.

With painstaking care,

they transferred the jumbled bones to their lab

to begin the arduous process

of sorting through some 50,000 fragments.

Meanwhile, Mike took a closer look at the pit itself

and found evidence

that indicated a surprising new chapter

in the story of Stonehenge.

That story begins 5,000 years ago,

before Egypt built its pyramids.

It was Britain's Stone Age,

when a flourishing agricultural society,

despite having no modern technology,

managed a marvel of ancient engineering.

A circular ditch and bank surround the enormous stones.

Upright pillars tower over 20 feet

and weigh at least 40 tons.

Horizontal slabs, called lintels,

form huge archways.

All these giants are made of sarsen,

a local sandstone harder than granite,

yet they were carved and fitted like woodwork.

Uprights were tapered and topped with knobs.

These fit hollows on the bottoms of lintels.

Curved lintels, joined by tongue-and-groove,

formed a nearly perfect circle.

And despite a slight slope,

this ring of lintels was level to within inches.

The sarsens dominate Stonehenge,

but nestled among them are smaller stones,

no less remarkable.

Geologists determined these are bluestones,

transported here from Wales, 180 miles away.

So who built Stonehenge?

The identity of the builders has always been a mystery.

Will the bones that Mike Parker Pearson's team

has found in the burial pit help solve it?

After removing the bones,

they find a clue at the bottom of the pit.

What we have here

is an area that is really quite smooth and flat,

but it's got lots of crunched-up pieces in it,

whereas around it, we have this blocky type of chalk.

The chalk at the bottom of the pit

appears to have been under pressure

from something extremely heavy...

Perhaps the base of a stone.

What happens when you put a great big stone vertically

into a place like this,

it actually crushes the chalk, so it loses its structure.

It really does look as though

this is going to be the position within the pit

that the stone was actually placed.

So it has to have been fairly slim, narrow stones

put in those holes,

and at Stonehenge, there's only one candidate:

It could only be the bluestones.

Mike suspected

that the bluestones now grouped in the center of the monument

had once stood in the outer ring of pits,

where the cremated bones were found.

The bone fragments were buried in the pits

alongside the stones,

and they were crushed down so tightly

that they picked up fragments

of the calcium carbonate, or chalk, bedrock.

It's a small piece of bone

completely encrusted with calcium carbonate.

So this has actually adhered to the bone

from the surrounding chalk environment.

The crushed chalk sticking to the bones

suggested that the burials occurred at the same time

the pits were dug for the bluestones.

Mike believes that makes the bluestones

even more significant.

I think it shows us something really important,

that there's a deliberate association

with somebody's remains and one of these stones.

It's almost like a gravestone.

Carbon dating of the bones

revealed that they were buried around 3000 BC.

Since it's known that the enormous ring of pillars

was not erected until 2500 BC,

this means that the bluestones and the burial pits

were the very first structures at Stonehenge.

This fundamentally changed the accepted view

of how we looked at Stonehenge.

Mike's evidence showed

that Stonehenge has not always looked this way.

In fact, 5,000 years ago, when it was first built,

it looked like this...

...before the inner ring of giant sarsen stones

was put in place.

It was a huge prehistoric cemetery.

The bluestones marked the graves of the people

whose remains Mike's team is now analyzing.

So was there something special about the people buried here?

Who were they?

With the bone fragments laid out in the lab,

Mike and his team can begin their analysis.

First, they have to solve

a 50,000-piece prehistoric jigsaw puzzle.

They don't look like much.

It's hard to even recognize some of them as bones,

because they're fragments

that have come through the cremation process,

but if you look carefully with the expert eye,

you can see that they belong

to different parts of the skeleton...

The ribs, the vertebrae, the mandible, the skull...

The first question is, how many bodies are they dealing with?

Osteoarchaeologist Christie Willis

finds a telltale clue.

So the bones that we have found

that are most common throughout the collection

are the ear bones.

We have one on the left and one on the right,

and because of this, we're able to prove