All language subtitles for Ancient.Engineering.S01E09.Stone.Age.Secrets.1080p.AMZN.WEB-DL.DDP2.0.H.264-NPMS_track3_[eng]

[dramatic music]

- [Narrator] We are surrounded

by extraordinary
feats of engineering.

Constantly pushing the
boundaries of what's possible.

- Without engineering,
there'd be no modern world.

- [Narrator] Gigantic cities.

Amazing infrastructure.

And ingenious inventions.

- Engineering is the key to
turn dreams into reality.

- [Narrator] To reach
these dizzying heights.

Today's technology relies

on breakthroughs made
by ancient engineers.

- It's mind boggling
how they did this.

- [Narrator] How did
early civilizations build

on such a scale?

- They raised the bar
for construction in a way

that no one thought possible.

- The sheer engineering ability

that is in itself impressive.

- [Narrator] By defying
the known laws of physics

and daring to dream big.
[dramatic music]

They constructed
wonders of the world,

from gigantic pyramids

to awe-inspiring temples

and mighty fortresses.

All with the simplest of tools.

- Cannot imagine the skills
people would have needed

to build like this.

- [Narrator] Now it's possible

to unearth the secrets
of the first engineers.

- They managed to
construct edifices

that have survived
the ravages of time.

- [Narrator] And reveal how

their genius laid
the foundations

for everything we build today.

[dramatic music]

In every corner of the earth,

humans have created
huge monuments

carved from a material capable

of withstanding
the test of time.

Stone.

[dramatic music]

- Our ancestors certainly
understood the timelessness

and the monumental
qualities of stone.

- [Narrator]
Extremely hard wearing

and found almost everywhere.

Stone can also be
a thing of beauty.

[dramatic music]

These attributes have made
it the construction material

of choice throughout history.

Used in engineering marvels
built to mark great victories,

to celebrate national
values, or to honor heroes.

- People have come
together to build monuments

to celebrate, to have a place
to gather, to mourn the dead.

[dramatic music]

- They say a lot about
how society sees itself,

but more importantly,
they say a lot about how

a society would like
other people to see them.

[dramatic music]

- [Narrator] Iconic recent
examples include the monuments

of Washington, DC.

The National Mall is a series

of spectacular buildings
and structures.

A sacred complex in the
center of the capital city.

- Washington, DC is the
beating heart of America.

And the National Mall is the
beating heart of Washington.

- [Narrator] This is the setting

for great moments in
America's national story.

- It's a stage for
American democracy.

It's where the people

of America can come to
have their own voice.

[dramatic music]

- [Narrator] Each of
the mall's structures

is an engineering
triumph in its own right.

The Washington Monument, a
towering 555-foot obelisk.

The world's tallest
stone structure.

[dramatic music]

- The Washington Monument
is a very simple structure.

It's just marble blocks
stacked on top of each other.

It doesn't use mortar and it
doesn't use reinforcing steel.

So it has to be made
to very fine tolerances

so the blocks sit together.

[dramatic music]

- [Narrator] There's also
the Lincoln Memorial,

the Vietnam Veterans Memorial,
and the Jefferson Memorial.

The entire complex has
been precision engineered

to be geometrically aligned.
[dramatic music]

- The monuments are
laid out in a way

that you're able to see and
get get these great vistas

from multiple
different directions.

[suspenseful music]

- [Narrator] These stone
monuments were built to last,

using precision engineering.

But they incorporate
lessons learned

from ancient engineers
whose earliest structures

still standing today were
built back in the Stone Age.

[suspenseful music]

[wind whooshing]

[suspenseful music]

Stone monuments date

from the very dawn
of civilization.

In the prehistoric period
before written records began.

- Stone monuments aren't new.

They're something that's
been going on since 9,500 BC.

- [Narrator] This period known

as the Stone Age
produced monuments
that still stand today.

[suspenseful music]

With individual components
reaching as high as 30 feet

and weighing up to 25 tons.

Some are engineering enigmas.

- You cannot stand there

without questioning
how it was achieved.

- [Narrator] Remarkably,
ancient engineers constructed

these monuments before the
invention of metal tools

or even the wheel.
[dramatic music]

- We're looking at
substantial amounts of labor.

And that is something
that is just unmatched.

- [Narrator] Their origins

have long been
shrouded in mystery.

Little is known about the people
who built these structures

and to what purpose, but
science is now starting

to unlock the
engineering secrets of
these ancient wonders.

[dramatic music]

[suspenseful music]

One of the earliest at
greatest prehistoric monuments

is found on the wild coast of
Brittany, Northwest France.

Carnac.

The monument dates
from around 4,500 BC

in the Neolithic
or Late Stone Age.

- Carnac is one of the great
wonders of the Neolithic world.

- [Narrator] It's
thought to be the oldest

of Europe's stone megaliths.

Over the course of a millennia,

Stone Age people, believed
to be hunter gatherers,

place an extraordinary
10,000 stones upright

in the ground at Carnac.

- Carnac is one of a
number of stone rows

that we find in Brittany
from that prehistoric time.

It's simply the
grandest, the biggest,

and the most elaborate.
[dramatic music]

- [Narrator]
Spanning a total area

of over five square miles.

It's also the largest collection

of megalithic standing
stones anywhere in the world.

They're laid out in
long parallel rows

and in strange
semicircular arrangements.

- The big, distinguishing
feature of Carnac is

that it has huge alignments

of standing stones.

Six, eight abreast,

marching across hundreds
and hundreds of meters,

turning corners and so on.
[dramatic music]

- [Narrator] It's
still unknown exactly

how ancient engineers
planned this monument.

But there's no doubt
it was a challenge.

Carnac is built on a vast scale.

This has helped give rise

to some extraordinary
notions over the centuries.

- One of the most
common myths and legends

that we have associated
with our stone circles

and our standing stones is

that these are petrified people.

People who are petrified

where they were performing
their ceremonies and rituals.

- [Narrator] While
it's likely Carnac

was built for ritual purposes,

nothing is known
of the actual rites

that may once have
been performed here.

[dramatic music]

Some have even speculated

that Carnac could be a kind
of astronomical calendar.

But built long before
any written language,

there's little
evidence for this.

In fact, the only remnants
from the Stone Age

are the stones themselves.

[dramatic music]

Ranging from three
to 20 feet in height.

Many are formed
of solid granite,

quarried from the local area.

This rock is an
extremely tough material.

It's a mystery as to how
Stone Age hunter-gatherers

had the engineering ability
to shape these blocks.

[peaceful music]

But there is evidence of some

even more complex
engineering dotted

around the Carnac site.

[suspenseful music]

Dolmens.

These are thought to
have been covered mounds

when originally constructed

and at least 50 are spread
out across the area.

- The dolmens tend
to be monuments

where a large capstone,

sometimes upwards of sort
of 40, 50 tons is raised up

on other upright stones in
order to create a chamber.

- [Narrator] The
design is substantial,

with heavy supporting blocks
topped by a massive capstone.

- Just the engineering
of actually producing one

of these is quite phenomenal.

It's kind of

like building Stonehenge
times 10 I think sometimes.

[suspenseful music]

- [Narrator] Maneuvering
these stones into position

would have required engineering
know-how and planning.

One theory is that the huge
capstones weren't moved at all,

but were already in situ.

[dramatic music]

- The stones from Carnac
were most likely gathered

in the locality.

A scenario that is strewn

with granite boulders
and other forms

of other nice shaped stones.

So they had the ideal
resources immediately to hand.

[dramatic music]

- [Narrator] Ingenious
neolithic engineers

would then have tunneled
beneath each side,

before sliding smaller
supporting stones into position.

- Just the way that it's
constructed is amazing.

You would have these
standing stones

to create, I suppose, the walls.

So that would then
be the foundation for
the outer chamber.

And also the capping.

[suspenseful music]

- [Narrator] Tunnels were
then dug into the structure

and a chamber excavated
beneath the capstone.

It's believed they may
have been collective tombs.

Although, in the acidic
soils of Brittany,

no trace of human
remains has survived.

[suspenseful music]

Their true purpose
may never be known.

There's no doubt

that excavating these
chambers was backbreaking work

with the limited
tools available.

But some of the basic
principles pioneered

in Stone Age France have evolved

into engineering
techniques used today.

[dramatic music]

[wind whooshing]

[upbeat music]

Even in the modern
era, tunneling can
be a daunting task.

[machinery clanking]

It's a construction process
that's still essential.

Though today, transport,

rather than tombs,
are the priority.

The best place to put a railway

in a crowded modern city is
in a tunnel below the ground.

But that's not straightforward.

- The big challenge of
building underground railways

is how do you make the hole.

To try and create tunnels

underneath cities is
hugely challenging.

- [Narrator] The first
underground railways

were built using a technique
known as cut and cover.

- You literally cut a hole,

a sort of a ravine
into the ground.

Put brick sides on it.

And then you cover it again

once you've got the
tunnel underneath.

[upbeat music]

- [Narrator] But this approach

caused disruption above ground.

Sometimes meaning entire
buildings had to be demolished.

[explosion booms]

So engineers developed
a technological wonder.

A machine for
boring out tunnels.

Also known as the mole.

- The great innovation in
tunneling was the invention

of the tunnel-boring machine.

Basically it's a shield
that allows you to dig away

at the front while protected
from the ground collapsing

on top of you

- [Narrator] The
subterranean monsters

reach almost 300 feet in length.

Weight over 6,000 tons,

and exert a monstrous
25,000 brake horsepower.

Hydraulic jacks
generate forward thrust

while a rotating cutter
head claws the material

from the tunnel face.

It can dig through either
earth or solid rock

and a conveyor belt shifts
the loosened material

to the back of the machine.

In this way, the mole cuts

over 230 feet of
tunnel in a single day.

And best of all,

these machines have little
impact on the surface.

- The great benefit of the
tunnel-boring machine is

that the people above basically
don't know you're there.

Life can carry on above as
if nothing is happening.

[upbeat music]

[machinery whirring]

[stone rattling]

[suspenseful music]

- [Narrator] In the Stone Age,

such equipment would have
seemed like some form of magic.

But despite their
rudimentary technology,

prehistoric builders managed
to create engineering marvels.

One remarkable monument
lies over 400 miles

across the ocean from
Carnac in Ireland.

Newgrange.

Built around 1000 years after
the construction of Carnac,

it's evidence of a huge stride
forwards in engineering.

[suspenseful music]

- Newgrange is a passage tomb
on the east coast of Ireland.

It's a monument that was
built round about 3000 BC.

So now we're talking about
the Middle Neolithic period

and it's a tomb that was
incredibly sophisticated.

It's huge.

- [Narrator] This is a
burial chamber far bigger

than those that had gone before.

[suspenseful music]

In total, it's made up of
around 200,000 tons of rock.

To construct the inner chamber,

ancient engineers used a
technique known as corbeling.

Overlapping stones that
gradually narrow as they rise

until a capstone can
be placed on top.

[dramatic music]
At 270 feet in diameter,

43 feet high, with a 62-foot
chamber concealed inside,

this is a truly
enormous structure.

Some experts believe this
was a major ritual center,

but others argue it was
more straightforwardly

a burial place.

- It's one of the largest
passage tombs in Ireland.

And it was used, we think,
for the burial of the dead.

Mostly cremations.
[dramatic music]

- [Narrator] Not all
archeologists agree

that Newgrange was a tomb.

Though fragments of bone
have been discovered

in the passage way.

Remains of possible grave
goods have also been found.

But Newgrange's greatest
engineering secret

was only revealed in the 1960s.

Archeologists identified a
curious decorated structure

above the tomb entrance.

They named it the roof box

and realized it
had been designed

for a very specific purpose.
[dramatic music]

[suspenseful music]

Ancient engineers constructed
the passageway leading

into the tomb with
great accuracy.

To channel light
from the roof box

on the first sunrise
after the winter solstice.

- The light of the
sun just after it rose

around winter solstice would
have shone right into the tomb

and lit up the bones
of the dead inside.

[dramatic music]

- [Narrator] The floor of
the passage was designed

with a gradual slope.

So light from the
box could reach right

into the inner
chamber on this day.

It's an impressive piece
of precision engineering,

built into such a huge
and ancient structure.

What it tells us is

that there was some connection
going on in people's minds

between death, ancestors',
ancestor spirits,

on the one hand.

And the sun, seasonality,
seasonal renewal on the other.

- In order to build a monument

that aligns with the sun,

you need to have observed
the movements of the sun

over at least a year's period.

- [Narrator] This
discovery proves

that Neolithic humans were
becoming skilled engineers.

Pre-planning their projects to
yield extraordinary results.

[suspenseful music]

It's also evidence of
prehistoric knowledge

and understanding
of the sky above.

And the birth of astronomy.

[wind whooshes]

[stone rattling]

[suspenseful music]

Monuments throughout the
ancient world share alignments

with solar and
celestial objects.

Sun, moon, and certain stars.

From Uxmal in Mexico

to Egypt's Great
Pyramid and Chaco Canyon

in the Southwest United States.

The reasons why this was done
remain shrouded in mystery.

Ancient people may have used
astronomy to create calendars.

Important for the
agricultural season.

[suspenseful music]

Other reasons could have
been more mythological.

Long-forgotten ancient
beliefs and rituals.

Whatever the purpose, early
people went to great lengths

to engineer their monuments
to reflect celestial events.

- The sun and stars have been

so important to
humans for millennia.

- [Narrator]
Humanity's fascination

with the sun and stars hasn't
diminished in the modern era.

But while Stone Age people
could only observe the night sky

with the naked eye, subsequent
engineering developments

have led to vastly
superior tools.

The greatest breakthrough
came with the invention

of the telescope in 1608.

Cue the renowned
astronomer, physicist,

and engineer Galileo Galilei.
[suspenseful music]

- Galileo's telescope
refracts light.

So it bends light.

And that's what gives
it the magnification.

- [Narrator] Galileo refined
telescope technology,

improving magnification
from three times

to 20 times that
of the human eye.

With these devices, he observed
the craters of the moon.

Saturn's rings.

Sunspots.

And Jupiter's moons.

Today's telescope engineers
continue to push the envelope,

making it possible to peer
ever further into deep space.

[suspenseful music]

- The engineers play a key role

in increasing the
understanding of the universe.

And one of the ways they do
that is working on telescopes.

- [Narrator] The South
African Large Telescope,

built in the desert of Karoo,

is one of the
biggest in the world.

Its huge hexagonal primary
mirror array measures

over 30 feet across

and contains 91 individual

three-foot-wide
hexagonal mirrors.

But no matter how large
a telescope becomes,

Earth's atmosphere and
shifting air pockets

will always distort light,
limiting observations.

Engineers once again
came up with a solution.

Put a telescope in space.
[suspenseful music]

- The Hubble Space
Telescope has been one

of the greatest things
we've ever done in space.

- The Hubble
telescope is very big.

I mean, it's the
size of a school bus

and it weighs several tons and
it presents a huge challenge

getting something of
that size into space.

- [Announcer] Four,
three, two, one.

And liftoff!
[rocket whooshing]

- [Narrator] Hubble was
assembled on earth before

being launched into orbit on
board the Challenger Shuttle.

From space, without the
atmosphere blurring its view,

the telescope has captured some

of the clearest,
most detailed images

of the universe ever seen.
[suspenseful music]

[wind whooshing]
[stones rattling]

Prehistoric astronomy
was limited in comparison

to modern-day space exploration.

But Stone Age people
weren't the thuggish caveman

they're sometimes thought to be.

[suspenseful music]

Some of the engineering
achievements they've left behind

provide evidence of a
highly complex way of life.

- I think people think

that prehistoric people
are really unsophisticated,

but I think that's really
far from the truth.

You have these very complicated,

intelligent,
community-based societies.

- [Narrator] One of the best
spots to see this is Orkney.

Off the Northern
tip of Scotland.

It's a storm-lashed
place of rugged cliffs.

Today it seems a remote
part of the world

on the very edge of the map.

But 5,000 years ago, Orkney lay

at the center of trading
routes, running all the way

to Europe via the North Sea.
[suspenseful music]

And the Stone Age people
living on these islands

were taking great strides
in ancient engineering.

- 5,000 years ago, Orkney
was an astonishing center

of innovation and invention.

It's like the Silicon
Valley of the Neolithic.

[dramatic music]

[suspenseful music]

- [Narrator] One intriguing
site was revealed back in 1850

when a great storm
stripped grass

and earth from a large mound.
[suspenseful music]

It exposed the outline of some
substantial stone structures.

Excavation showed
them to be a series

of interconnected houses.

At first, nobody was sure
quite how old they were

but radiocarbon dating proved

they'd been built in
the late Stone Age.

- The structures in Orkney
were unlike anything else

in the British Isles.

They were very, very complex
and beautifully made.

[suspenseful music]

- [Narrator] This site, known
as Skara Brae, is evidence

that prehistoric homes
were far more advanced

than had been thought.

- Skara Brae tells us an awful
lot about the settlements

of these people because
it's built out of stone

and we can see all the
detail of what's going on it.

[suspenseful music]

- [Narrator] It's thought
that approximately 50 people

would have lived in the houses.

Finds include jewelry,
needles, dice, and buttons.

But no weapons have
ever been discovered,

suggesting these were
peaceful farming people.

They must, at some point,

have migrated here
from the mainland.

Remarkably, their 5,000 year
old homes were constructed

with many of the creature
comforts enjoyed today.

[suspenseful music]

- Archeologists have
found the bed boxes,

the little dressers.

The hearths, boxes set into
the floor for storage of food.

- [Narrator] Incredibly,
the houses of Skara Brae

were built without the
use of mortar or cement.

Their walls have an inner
and outer layer of stone,

thought to be filled with
some form of insulation.

And these homes are just one

of several remarkable
prehistoric monuments on Orkney.

Nearby, the tomb of Maeshowe.

Just like Newgrange,

its entrance passage
is carefully engineered

to align to the
winter solstice sun.

[dramatic music]

There's also the
spectacular Ring of Brodgar.

Measuring over 300
feet in diameter,

with stones up to 15 feet tall.

Only 27 of the original 60
stones remain standing today.

But their size is
testament to the skill

of Orkney's ancient engineers.
[peaceful music]

[wind whooshing]

[stone creaking]

[upbeat music]

In the modern world,

architects are still drawn
to the circular form.

- The circle represents a
number of things to humans.

It could be unity, focus,
infinity, inclusion.

It's a very powerful symbol.

- One of the best known examples

of circular buildings
is Apple Park

in Cupertino, California.

Designed by Sir Norman Foster,

this is the super
high tech headquarters

of the vast multinational.

- The Apple building
is a perfect circle.

Apple co-founder, Steve Jobs,

wanted his office building
obviously to stand out,

to be unique, but
also he wanted it

to not feel like
an office space.

To have that innovative feel

and allow people to really
think outside the box.

- [Narrator] The structure
forms a perfect ring

a mile in circumference.
[upbeat music]

but ring shaped or
circular designs

can give rise to complex
engineering problems.

- Circular geometries
present challenges

for modern construction.

Most of the stuff
we make is flat

or straight or right angled.

- [Narrator] 3000
curved panes of glass

were custom engineered
for Apple's HQ.

At 49 feet tall,

these are the largest curved
glass panels in the world.

Luckily, with so much glass,

the building is
earthquake proof.

It uses base isolation
technology to reduce shaking.

The entire structure resting

on 692 huge stainless
steel saucers.

It can move as much as
four feet in any direction.

This is one

of the reasons Apple
Park is thought

to have cost around
$5 billion to build.

The immense,
light-filled glass circle

has already become
an engineering icon

of the digital era.

[wind whooshing]

[stone rattling]

[suspenseful music]

But a very different
circular structure is hailed

as the greatest engineering icon

of the prehistoric period.

A mysterious and
complex monument dating

from around 3000 BC.
[suspenseful music]

Stonehenge.

[dramatic music]

- Stonehenge is an
icon of prehistory.

- When you stand and look
at these incredible stones,

you can only feel
awe and wonder.

[dramatic music]

- [Narrator] The monument
makes striking use

of enormous stone blocks.

Some as tall as 30 feet.

Weighing up to 25 tons.

[dramatic music]

- The construction of Stonehenge

is an astonishing achievement.

It's amazing that they
even conceived of the idea,

let alone actually
managed to build it.

- [Narrator] Before the
arrival of paved roads

or even the wheel to Britain,

this was a major
feat of engineering.

[dramatic music]

- It's something that happened

over a very, very long period.

It roughly took about
a thousand years

to create this huge monument.
[dramatic music]

- [Narrator] Exactly how
did ancient engineers

pull off the
seemingly impossible?

[suspenseful music]

First step was to
identify a site.

And Salisbury Plain
had obvious advantages.

The high, open area
was the ideal spot

for a striking monument.

It would be visible
for many miles around.

[suspenseful music]

- We know that the
Salisbury Plain area

was this chalk upland

where potentially not as
many trees were growing,

as in other parts
of Southern England.

[suspenseful music]

- [Narrator] The first
stage in the construction

of Stonehenge occurred
around 3000 BC

when ancient engineers
dug a huge circular ditch

and raised bank.

[suspenseful music]

- Actually creating that
was quite a big deal.

It's just the
amount of man hours.

- [Narrator] The bank
at Stonehenge forms
a massive circle

over 350 feet in diameter.

And the ditch itself
is wide and deep.

It was cut into
tough, chalky soil

without the benefit of
modern digging equipment.

- These people don't have a JCB.

They don't have shovels.

They don't have mattocks.

- [Narrator] Archeological finds

from across the site provide
clues to how it was done.

Antlers.

Deer antlers are
formed of tough bone

with sharp points
making them ideal

for cutting into chunky ground.

- It is quite an
astonishing feat

that people managed
to dig out chalk

using simple antler picks.

- [Narrator] But this still
wouldn't have been an easy task.

It's estimated that excavation

of the ditch alone could
have taken a workforce

of up to 4,000 people
several months to complete.

Recent finds suggest
that workers lived nearby

in a settlement known
as Durrington Walls.

Over 1000 dwellings have
been identified here

and it's believed
people may have come

from far and wide to help.

[dramatic music]

[stone rattling]

[suspenseful music]

It's not known exactly when
Stonehenge got its first stones,

but many were in
place by 2,500 BC.

Two main types were used.

Smaller bluestones and
the larger sarsen stones.

- The bluestones at
Stonehenge represent

the first significant stone
works to be erected on the site.

Before then, it
was earthen works.

- [Narrator] Only in 2015
were scientists finally

able to pinpoint exactly where
the bluestones originated.

- Geologists have managed
to chemically match them

to the Preseli Hills.

- [Narrator] The Preselis
lie in West Wales,

over 140 miles from Stonehenge.

[suspenseful music]

And the unique
geology here makes

this the only possible
source of stone in Britain

for the Stonehenge bluestones.

- The bluestones themselves
look very distinctive.

They're this very
dark gray-blue color.

And most of them have
this quartz fleck in them.

[suspenseful music]

- [Narrator] But how did
ancient engineers extract

the massive four-ton blocks?

The recent discovery

of the original
Stonehenge quarrying site

offered archeologists
vital clues.

- What they have
noticed is that there's

these huge fissures
in the rocks.

And they're actually
taking advantage

of these cleaving points.

[dramatic music]

- [Narrator] Analysis shows
that neolithic engineers

likely hammered large wedges
into the many cracks running

along the top of the pillars.

- They were probably
using wooden wedges

which they could
make wet and expand

to ease out and lever the stone.

- [Narrator] As the
wedges expanded,

they'd split the stone,

enabling huge slams to be prised
away from the quarry face.

And this same basic
quarrying method

has been in use ever since.

[gears rattling]
[suspenseful music]

Even in the 21st century

- People doing
quarrying will try

and find the
fissures, recognizing

that that's where
the weaknesses are.

- [Narrator] But in
the modern world,

quarrying has evolved.

[explosions booming]
[intense music]

The introduction of explosives
in the late 19th century

changed the face
of this industry.

Explosives detonate to
produce powerful blast waves

and large volumes of gas.

Because they're
confined in a hole,

the expanding gases are
forced into existing cracks

and create new ones to
break the rock apart.

[explosion booms]

Mining engineers still
use blasting today

but explosives can
be inefficient,

pulverizing valuable material
along with unwanted spoil.

So more precise techniques
have also been developed.

[suspenseful music]

Crucially the use
of helicoidal wire.

- So they use helicoidal
wire saws in quarries

as a way of cutting

through relatively
soft rock like marble.

- It's essentially three wires

that are wound round each other

that you can accurately
cut through stone.

By creating a loop of this wire

that is driven around the stone

and gradually cuts through it

with some kind of
lubricant to cool it down.

[upbeat music]

- [Narrator] The
wire moves at speeds

of close to 50 feet per second.

Sometimes embedded with
diamond dust for extra bite.

- You can get very neat
cut and so it comes out

and needs relatively little
work to be usable afterwards.

[upbeat music]

- [Narrator] Once cut,
diggers push huge slabs

of stone free with
little wastage.

Thanks to this technique, the
world famous Carrara quarry

in Italy produces an
incredible 1 million tons

of marble per year.

But modern quarrying

can also have a major
environmental impact.

Some scientists blame it
for ground water pollution,

noise and air pollution,
and a loss of biodiversity.

[machinery rumbling]

[gears clacking]

[suspenseful music]

In prehistoric Britain,

the extraction of the bluestones

in South Wales using
natural fissures

was a stroke of genius.

But for centuries,
historians have struggled

to understand how engineers
transported the four-ton stones

over 140 miles to
Salisbury plain.

[suspenseful music]

- The bluestones must've
meant something more

than just practical reasons.

Otherwise you wouldn't
bring them over 200 miles.

- [Narrator] In early 2021,

new evidence appeared
to provide an answer.

Archeology showed that,

long before Stonehenge
was built in England,

the bluestones had
first been erected

as a stone circle in Wales.

Close to the quarrying site.
[suspenseful music]

- It may be that the people
who built Stonehenge saw

the Preseli Hills as
their ancestral home.

It may be that that was a
particularly sacred place.

These mountains
were special places.

Places of the gods.

- [Narrator] Centuries later,

this original circle
was dismantled.

- The current theory is
that when the monument

was then dismantled

that they were then transported
and reused in Stonehenge.

- [Narrator] Whatever
the circumstances,

transporting the stones
was a mammoth undertaking.

And a huge
engineering challenge.

In an age before road networks,

sea transport seems

to have been the obvious
way of moving them.

[suspenseful music]

- We've assumed in the
past that the easiest way

to move one of these
bluestones would be

to get it down to the coast,

put it on some kind of
neolithic boat or raft.

- You would have gone

down the Pembrokeshire coast
into the Bristol Channel.

- [Narrator] This route
would have involved

ferrying the stones
across the channel,

leaving just a short
distance to cover by land

before reaching Salisbury Plain.

But experimental archeology

has highlighted the
dangers involved.

[suspenseful music]
- Back in 2000,

a Millennium grant was given
to a team to try just that.

It didn't go well.

They'd only got half
a mile out to sea

at Milford Haven
when the thing sank.

[water whooshing]

[suspenseful music]

- [Narrator] In 2012,
a second attempt

proved more successful.

But it seems unlikely

that the stones were
transported all the way by sea.

Many miles of the bluestones'
journey to Salisbury Plain

must've been by land,
across a variety of terrain.

[peaceful music]

- It would have had to be
a massive group effort.

Yes, you can do it.

But I think the scale of that

and the organization level
would have been huge.

[suspenseful music]

- [Narrator] To understand
how it may have been done,

students from University
College London carried out

some experimental archeology.

Attempting to become
megalith movers.

Previously, many experts
thought log rollers were used.

But the team believed
a different approach
was more likely.

They used a cradle
to hold the stone

and attempted to slide this
load along the track way.

- They were building
a short stretch

of timber track way
and experimenting

with the stone that was
attached to a cradle over that.

And they were really
surprised by how easy it was.

[suspenseful music]

- The experiment
showed that groups

of just 10 people could
move a large stone.

Far fewer than
experts had predicted.

However, vast numbers
of workers would still

have been needed.

Perhaps over 3000
at any given time.

- That level of organization
is quite phenomenal.

Just to think about it.

You would have to
have organized teams,

almost like a relay race.

[people cheering]

[suspenseful music]

- [Narrator] The successful
delivery of the bluestones

to Salisbury Plain was
a great achievement.

But Stonehenge was far from
the only stone circle built

in this period.

They were constructed
all across Europe

in the Neolithic era.

Surviving to this day at sites

such as the Gulf of Morbihan
in France, Avebury in England,

and Almendres
Cromlech in Portugal.

Some archeologists
believe they were built

as temples or ritual
gathering places.

Whatever the purpose
of these monuments,

there's no doubt that
Stonehenge continued

to grow in importance.

[dramatic music]

[stone rattling]

[suspenseful music]

The next major phase
of construction

at the site took
place towards the end

of Britain's Stone Age.

And made the monument
into the famous shape

that's still visible today.

To achieve it, eight additional
features would be added.

Among them, the five
world famous trilithons.

Groups of two
uprights sarsen stones

with a third set
horizontally across the top.

They're the largest of
all the Stonehenge stones,

weighing up to 30 tons a piece.

- When the huge stones arrived,

that was the time
when Stonehenge became

something completely unique.

Unimaginable effort was put

into those incredible
feats of engineering.

- [Narrator] Unlike
the bluestones,

the massive sarsens seem to
have been found close to hand.

- Recently there's been research

with geochemical
techniques on these stones

and sourced the exact
location of them.

A place called the West Woods.

[dramatic music]

- [Narrator] West Woods lie
on the Marlborough Downs,

just 15 miles from
the Stonehenge site.

It's thought that another
trackway was built

to move the sarsen blocks.

Probably taking several
years to construct.

For prehistoric people,
transporting stones on the scale

was a truly awesome
feat of engineering.

- For them, this would have
been like the moonshot.

The most amazing thing
that ever happened

to create a wonderful structure.

[dramatic music]

[wind whooshing]

[stones rumbling]

[suspenseful music]

- [Narrator] 4,500 years later,

preparing for the
actual moonshot.

NASA engineers also face
the daunting challenge

of moving a gigantic load.

One that dwarves Stonehenge.

The Saturn V.

[upbeat music]

The largest rocket ever built.

Weighing over 6 million pounds,

it's as tall as a
36-story building.

Simply moving this monster

to the launch pad was
an engineering feat

in its own right.
[upbeat music]

Technicians had

to design a gigantic
new vehicle to do it.

The crawler-transporter.

- It's this incredible machine.

It's got these huge
caterpillar tracks

and then a self leveling top.

That means that it can
carry the Saturn V rocket

whilst keeping it steady.

- [Narrator] The transporter

is actually the largest
self-powered land vehicle

in the world.

131 feet long, weighing
over 2,500 tons,

and costing $14 million.

It even uses laser guidance
to ensure perfect accuracy

when docking at the launch pad.

The combined weight of rocket

and transporter would have
damaged ordinary roadways.

- NASA had to create
essentially an airport runway

for this vehicle to travel on.

It couldn't travel
on normal roads.

- [Narrator] Engineers built

a heavily reinforced
crawler way.

Two 40-foot wide lanes,
just over four miles long.

It was constructed with a
layer of Alabama river rock.

Up to eight inches thick.

Sitting atop four feet
of graded, crushed stone.

On this solid base,
the Apollo rockets took

their first careful steps

on the long journey to the moon.

[rocket whooshing]

[wind whooshing]
[rocks rumbling]

[suspenseful music]

The completion of Stonehenge
in around 2200 BC marked

the end of Stone Age Britain
and the dawn of the Bronze Age.

Over the next few centuries,
metal tools were used

to make carvings on the stones,

no longer visible
to the naked eye.

But there's one final
engineering secret

built into the
fabric of Stonehenge

that lay hidden until
the 18th century.

[suspenseful music]

The monument is
perfectly aligned

with summer and
winter solstices.

- Stonehenge is very
carefully constructed

so that sunrise on
midsummer's morning,

the shafts of light comes
straight down the solar axis,

right next to something
called the Heel Stone,

which is the largest
stone in Stonehenge.

[suspenseful music]

- [Narrator] A two-mile-long
formal approach

to the monument is perfectly
aligned with both solstices.

On Midsummer's Day, the sun
rises over the outer Heel Stone

and is beautifully framed
by the upright sarsens.

Prehistoric engineers
must've carefully observed

and charted the skies to make
such an alignment possible.

Further evidence of
their sophistication.

[suspenseful music]

- It's the notion
of how intelligent
people were back then.

How in touch they
were with nature.

How much that they understood
their surroundings.

[suspenseful music]

- [Narrator]
Knowledge of the sun

was vital for early farmers.

And some have argued
this is one reason

behind the monument's
construction.

It may also have been
a gathering place

or temple for those
celebrating the solstice.

- They may have had
religious beliefs

that met that during the
longest night of the year,

you had to perform certain
ceremonies and prayers

and incantations to make
sure the sun came back.

[dramatic music]

- [Narrator] Even today, as
many as 10,000 people come

to Stonehenge to watch
the magic moment planned

by ancient engineers.

[dramatic music]

Before written history began,

prehistoric people left
their mark on the planet.

The Stone Age monuments
still standing today prove

that ancient humans
were sophisticated,

highly skilled, intelligent.

From Skara Brae to
the Newgrange Tomb,

engineering principles
were shared and enhanced.

Culminating in the
wonder of Stonehenge.

To this day,

these ancient monuments
mesmerize millions.

Reminders the triumphs of
the first ancient engineers.

[dramatic music]