Underground Marvels (2019–…): Season 2, Episode 7 - Medieval Maze of Secrets - full transcript

[narrator] A mysterious
underground tunnel system

lies below an ancient city
in southwest England.

It's got quite a lot
of medieval graffiti on it.

[narrator]
What was its purpose

and how has it evolved
over time?

Thousands of miles away,
in Vermont,

is a subterranean complex
that's rock solid

and has been at the forefront
of its industry for over a century.

[narrator] And buried under
the tiny country of Moldova

in Eastern Europe,
is a massive underground city

stocked with barrels
of liquid gold.



[narrator] Throughout history

life underground
has captured our imagination.

It creates very frightening but
also very beautiful experience.

[narrator] Now, we're taking
you further and deeper.

There's all kinds of wild theories
about what could be below.

[narrator]
To unearth the mysteries

of these Underground Marvels.

Beneath the modern day
city of Exeter

in southwest England,

lies a hidden world
of medieval engineering.

There's no escaping here,
it's an impressive affair.

[narrator] Spanning nearly
1,400 ft. across the city,

this network of ancient
underground passages

provided locals with access
to a vital natural resource.



How did this ambitious
infrastructure project

help save lives during one of
the deadliest epidemics in history?

[Mark] A terrifying disease
sweeping across Europe.

[narrator] And how is the
system evolving for the future?

There's modern bricks
and concrete adjacent

to a passage which dates
from the 14th century.

[narrator] Buried 20 ft. under
the bustling streets of Exeter

are the remains of a network of
tunnels with a fascinating story to tell.

You'd never believe that
in this unpromising setting

there actually is a very fascinating
medieval world tucked away out of view.

[narrator] Accessed through
an unassuming entrance...

this maze of passages
stretches right across

the center of the city.

Just as we come through here

into the first bit
of the passages,

it's a really
interesting stretch.

[narrator] Archeologist
John Allan is an expert

on the city's ancient
subterranean tunnel system.

This is a little bridge
underneath Medieval street.

The street itself is all
gone, of course,

but you can see here that
they made special effort

to build a vault,
which is maybe these blocks.

They're very nicely finished

with a fine chisel
around the year 1350.

[narrator] Before this
impressive system was built,

Exeter's water supply came
from natural springs at the surface.

Allowing early inhabitants
to establish a settlement.

But by the middle ages,
supplying Exeter with fresh water

became a huge
logistical challenge.

Professor Mark Stoyle is an
expert on the region's rich history

and evolving infrastructure.

[Mark] During the 1100s
the cathedral first decided

to build a gravity flow aqueduct

and it's partly for prestige,
but it's also, of course,

because these great
monastic houses and cathedrals

needed a lot of water
for ritual purposes.

They also needed them
to supply the senior clergy

with piped water of their own,
which was a great luxury.

[narrator] By the 12th century,
as this city's population increased,

so had the need
for more clean water.

The church enlisted engineers to
search for a new source of water

in the nearby city
of Saint Sidwell.

The earliest pipe system did indeed
just lie in a deep trench under the ground.

Waster was brought
into the city from springs

which lay
outside the city walls,

underneath the walls
where it would be distributed

from public fountains.

[narrator] The springs brought
water into the city via lead pipes,

buried beneath the ground.

But pumping the water
from Saint Sidwell

uphill to the cathedral
was a challenge.

So the medieval engineers
installed a siphon system,

similar to those used by the ancient
Greeks, Egyptians, and Romans.

Siphons allow water to be drawn
upward without the use of pumps.

A combination of gravity
and atmospheric pressure

forced the water through the
lead pipes as they climbed uphill.

By 1346, construction began on
Exeter's first underground section,

known as the Cathedral Passage.

[Mark] This lengthy passage
was built by cut and cover,

you first dig the trench

and then you'd line
the bottom of it

with stone and build
up walls in the bottom.

Then you need
to build the vaults,

which you do with wooden century

and once that's all set
you can backfill.

[narrator] These passageways
were carefully constructed.

First, lead pipes
were laid along the floor,

then the space was covered
with vaulting stones and filled in.

Manholes were also
constructed along the route,

allowing easy access
for the medieval plumbers.

[Mark]
You can see the foot holes

at the bottom
of a square manhole,

which raises up and we're
about five meters deep here.

[narrator] Even though the cathedral
passage delivered clean water

to Exeter's clergy,

it wasn't nearly enough to
supply the rest of the population.

[John] The town councilors were very anxious
to secure a water supply of their own

rather than to simply piggyback
on the cathedral system.

[narrator] From the scant
supply designated for the public,

the wealthy were allowed to have
water piped directly into their homes.

For everyone else,
the water that remained

was dispensed through a public
fountain known as The Great Conduit,

located at the center
of the city.

[John] They also had
lots of deep wells

which they called tongue pits,

those became increasingly polluted
by human effluence and so forth.

[narrator] By the 15th century,
in response to public outcry,

a second underground
water system was built

large enough to serve
the entire city population.

[Mark] We're in a structure which is
now called the East Gate Chamber,

and this is the earliest part
of the city passages in Exeter.

Behind me, here, you can see the
foundations of the old Exeter East Gate.

If we look up here,
um, just above me,

we can see
the original medieval door

which gave access
to that chamber

that we think was probably
built in about the year 1420.

And you can see
a set of stone steps

leading down
into the chamber itself.

[narrator]
Today, local historians

and underground enthusiasts
like Mark

are still uncovering new finds.

[Mark] It's actually
the original medieval housing

for the lead pipe
of the city aqueduct.

And so, when the pipe
emerged from this little chamber,

it did so through this
big square stone

which has this beautiful hole
in the middle.

It's got quite a lot
of medieval graffiti on it.

[narrator] The siphon system was
expanded over the next few hundred years.

[Mark] During the reign
of Henry VIII,

the system was expanded
to Carfax,

the great central crossroads
of the city,

where a splendid ornate
fountain was erected

from which all of the citizens
could come to collect their water.

[narrator] Despite the
political turmoil during this time,

the underground tunnels
lying below the city

survived for centuries,
largely intact.

However, in the 1600s, during
the middle of the English Civil War,

Exeter's precious water supply
was compromised.

[Mark] The reigning
authorities in Exeter

decided to declare
on the side of parliament

and turn the city essentially
into a fortified stronghold.

[narrator] Residents grew
concerned that the opposition forces

would sneak into the tunnels

and either cut off
the critical water supply

or gain access into the city.

[Mark] They feared
that it was possible

that royalist conspirators
might get into these vaults

and somehow use them either
to blow up the East Gate itself

or to force a passage
into the city, underground.

[narrator] The lead pipes were
removed for casting into bullets

and the passages
where filled with debris.

[Mark] The conduit houses,
the banks on which the parts ran

were broken up and destroyed.

The trap doors were broken up
and burnt for firewood.

By the time the city
surrendered in 1646

and the parliamentarian troops
marched in,

Exeter systems
of public water supply

had been effectively destroyed.

[narrator] After the war ended

the vital water system
was repaired and restored.

By the 19th century,

the underground network
saw yet more change

when a deadly epidemic
wreaked havoc on the city.

[narrator]
In the fall of 1831,

cholera was spreading
like wildfire across Europe,

and Exeter officials
began to prepare the city

for the disease,
when and if it arrived.

A terrifying,
uh, disease, cholera,

uh, was sweeping across Europe.

Uh, the citizens in Exeter,
like, people in the cities

and towns all over England, they
knew that it was heading towards them.

[narrator]
Once the connection was made

between unsanitary water
and cholera,

the board of health acted fast

and commissioned local
engineer James Goldsworthy

to make some updates
to the passages.

Goldsworthy went right back,
uh, to basics.

He went back to the well heads

from where the water was
brought, he sort of reedified them.

[narrator]
To improve water flow

they changed
the position of the pipes.

[Mark] They dug the floor
of the passages much deeper

in order to allow the pipes
to be laid lower down.

You can see here,
this is a section where,

uh, the original floor would probably
had been about here in the passage,

it's been substantially
cut away to make,

uh, the trench much deeper.

[narrator] By this time
engineers had learned

that lead pipes
could lead to poisoning.

So Goldsworthy replaced
them with cast iron ones.

[Mark] The whole shape
of the passages is changed

into more like a coffin shape.

This is a result
of Goldsworthy's work.

The top of the passage
is still Tudor work,

but the bottom
is very much 19th century

and that's why it's got
such a different profile,

to the initial medieval section.

[narrator] The passages continued
to supply water to the city until 1857

when one of the wells
was damaged

during the construction
of Exeter's railway.

By 1901, the passages
had been abandoned,

but not forgotten.

Nearly 700 years after
they were originally built,

the tunnels were repurposed
to serve a new function.

[Dave] In 1942, Exeter
suffered terrible damage

following Baedeker raider Blitz,

and a lot of the medieval city was lost
in the center, and the sites were cleared.

[narrator] Hitler was enraged
by the Royal Air Force's bombing

of historic German cities.

So he decided to launch
a series of raids

on some of England's most
beautiful, but strategic towns.

Exeter was one
of the first to be hit.

The two nights of intensive
bombing left the city devastated.

Some had taken shelter
in the tunnels,

but above ground
the city was annihilated

and 265 people were killed.

Following this fateful night
much of the city was rebuilt,

and by the end of the war

the underground tunnel network
was rediscovered.

Dave Adcock is part of a team

tasked with protecting
the tunnels,

while the city undergoes
new construction above.

It's important that we preserve
this scheduled, ancient monument

to make sure
no damage, um, happens.

The developers had to follow
certain rules and regulations

in relation
to protecting the passages.

But you can see there's
modern bricks and concrete

adjacent to a passage which
dates from the 14th century.

[narrator] Striking a balance between
preserving the old city below ground

while developing a modern one
above is no easy feat.

The area where we are now
is actually incredibly fragile

and we're very close
to the, uh, the surface.

So it was important throughout
development that no damage happened here.

It was protected,
we had vibration monitors,

we had a full structural survey,

and also just above here
we have crash pads,

so during the demolition no
damage occurred to the passages.

[narrator] What other hidden
mysteries still linger under Exeter?

That remains to be seen.

[narrator]
An unexpected natural wonder

is hiding a mile and a half
under Vermont.

Carved into the Dorset Mountains

is the entrance
to a mining shaft

that's been in use
for over a 100 years.

How did this area become
one of the largest suppliers

of the world's most
recognizable building material?

He used his political influence

to ensure that marble was used in
the United States' Supreme Court.

[narrator] How has modern
technology played a role

in producing
this coveted rock form?

Don't forget you got
another quarry above here.

[narrator] And how long
can these mountains

keep providing
a building material

that never seems
to go out of style?

[narrator] Marble is one of the oldest
and most beautiful stones on the market,

and it's just as popular today
as it was thousands of years ago.

Three of the seven wonders of the
ancient world were made from this stone.

The temple
of Artemis at Ephesus,

the Lighthouse at Alexandria,

and the Mausoleum at
Halicarnassus,

were all built
from the finest marble.

This classic rock form
remains a symbol

of opulence and luxury
throughout the world,

and this quarry in Vermont
has lots of it.

While the entrance to the mine
has been used for over a century,

a lot has changed since 1902.

Keith Millard
is the quarry manager.

[Keith] About 140 metrics tons of
marble is removed each day from this mine.

We only save about
70 metric ton of it,

the rest of it is thrown over the
bank 'cause of quality, cracks,

just because of defection
in the stone.

[narrator] The marble vein is
located at the base of the mountain,

forcing the original miners to dig
through the middle of the landmass

to extract the precious mineral.

[Keith] The purpose of the
quarry being underground

is you can never cost-effectively
move the overburden.

Overburden
here might be 150 ft.,

down the bottom of the
quarry is almost 700 ft.

By the time
you move the overburden

it wouldn't be cost-effective
to quarry this marble.

Quarrying methods up until 1970,

everything
was drilled and blasted,

and taken out
with cables and derricks.

From 1970 on
they're using heavy equipment

to remove marble from the earth.

Things are cut with chainsaws,

diamond segments,
diamond blades.

Make things more efficient.

[narrator] Due to the
hardness of diamonds,

this abrasion technique cuts
through marble almost effortlessly.

[Keith speaking]

[narrator]
Marble is difficult to mine...

- [Keith] You got it!
- Compared to mining for metal ore,

where extracting rock
fragments is standard practice.

Marble has to be pulled out in
the largest possible unbroken blocks

for maximum value.

[narrator]
But the solid blocks of marble

destined for consumer use
require some heavy lifting.

[Keith speaking]

When you're tipping it over,
go easy.

All right. It's all right.

Easy.

[thuds]

[narrator] Vermont is often
associated with pure white marble

and Danby quarries is
considered the finest in the world.

The marble has to be
extracted in large blocks,

which are difficult to move.

These beds run
at about a 45 degree angle,

so we're taking this
and we're following that bed.

So we're gonna cut it here,
we're gonna put a square on it,

we're gonna cut it over here.

We're trying to separate
these dark colors

so we can get
all this white right here.

That'd be 40 inches and then
when we're all said and done,

we'll have a nice square block.

[narrator] Another
remarkable characteristic

of Vermont marble
is its veining.

Luka is the general manager
of the quarry

and he's a geologist by trade.

[Luka speaking]

[narrator]
The rock begins as limestone,

then through
the metamorphic process

changes into the hardened, more
luxurious marble over millions of years.

[narrator] The rock here is part
of an ancient continental shelf...

that extended up the eastern side
of the North American continent.

[Luka speaking]

[narrator] Vermont marble
has played a key role

in building America
since the early 19th century.

And it would be difficult to find a
significant building or monument

that doesn't have Vermont
marble somewhere in it.

Peter Prvulovic is the
director of Danby Quarry

and has studied
its history extensively.

[Peter] Our quarry expands
three quarters of a mile

north to south and
roughly 600 ft. east to west.

So we're now in one of the
oldest sections of the mine.

The quarry was
originally opened in 1850s.

In 1880s is when Vermont
Marble Company took over

and most
of the production started.

[narrator]
Over time demand grew

for the versatile and
attractive building material.

By the early 19th century,

the residents of Vermont
were convinced

that marble was the key
to growing their economy.

Companies started popping up
along the marble belt

and producing
different types of marble,

and having their own shops.

The shops included
cutting the blocks,

polishing the pieces,

and shipping them
to other locations.

[narrator] But mining back then
wasn't the same as it is today.

Before modern equipment
and safety gear,

these caverns
were hot and dangerous.

In fact, the industry
didn't truly take off

until the innovations of one man

changed Danby from the
boutique quarry operation

into a global marble powerhouse.

In 1880,
many of the entrepreneurs

sort of joined forces
and created one large company,

it was known
as Vermont Marble Company.

It was headed by
Redfield Proctor.

They became one of the largest
corporations in the United States

and one of the world's largest
marble companies.

[narrator] Redfield Proctor
used his business success

to propel his political career.

Serving as governor of Vermont

and then secretary of war

under
President Benjamin Harrison.

He used his political influence

to ensure that marble
from quarries in Vermont

were used in many of the federal
buildings around the country.

Some
of the more notable structures

that were constructed
using Vermont marble

are the United States
Supreme Court,

New York Public Library,

the Arlington National Cemetery,

as well as many more.

[narrator] Making sure
they can continue quarrying

this timeless building material

requires the miners to ensure
the safety of this space.

So the Roman pillar method has
been around since the early 1900s,

uh, most of the pillars
are about every 40 ft. apart.

You're creating structure
to support the ceiling,

don't forget you've got
another quarry above here.

So, a lot of these pillars are
stacked one on top of each other

from one quarry
to the other quarry.

[narrator]
The positioning of the pillars

is vital to the structural
integrity of the mine,

and the site designers are
meticulous in their excavation planning.

[Keith] 3D mapping
helps us understand

where to chase the vein
through the mountain.

They are able to tell us

within one inch
of where we are structurally,

from lining pillars up
from one quarry to the other

to, "Where do we wanna
drill my phone line?"

"Where do I wanna put
my emergency things in?"

So it helps us in many things
because it's so precise

and lets us know to the inch
exactly where we are.

[narrator] This
environment is unforgiving

if you make one false step.

[narrator] But it's not just
the quantity and quality of rock

buried inside the mountain
that makes this marble unique.

It's what's operating
hundreds of feet below it.

[narrator] The marble mined
in this Vermont quarry

is considered some
of the best in the world.

The mine encompasses
various layers of marble

with different characteristics,

allowing operators to extract

over ten different
types of marble.

But even though Danby Marble
has been used in the construction

of famous buildings
all over the world,

what few people know is that
hundreds of feet below the ground,

inside the same quarry walls
where the marble is extracted,

is a fully operational
production facility.

In early 2000s we started
creating a factory

inside of the voids that have
been quarried in the past

to start producing our own material
into slabs and cut-to-size material.

So, this is a block
we've just removed

from the Bruck Quarry
and we're bringing it up.

Weighs about 65,000 lbs.

What he's doing is
he's trying to get that block

very nice and square on there

so we get every slab that
we can out of this block.

Right now they're mixing mortar

and put it underneath the block,

so, when the gang saw blades
go down through,

the slabs can't shift
or move side to side

and the gang saw [inaudible]

and they'll hold them upright
after they're all cut into 2CM slabs.

All right, guys, go ahead. Put
the cables around it, pick it up,

bring it down,
put it on the car.

[narrator]
To cut the marble into blocks

the quarry workers use
a giant cutting machine

that operates just
like a bread slicer.

So, basically, these blades...
[imitates blades slicing]

back and forth slice
this block into 3cm slabs.

These are diamond segments

that are soldered
onto these blades

that actually
cut through this marble.

The purpose of the water
keeps the gang saw blades,

the diamond gang saw blades

when they're going through
the marble, keep them cool.

Otherwise they'll heat up
and break.

[narrator]
Due to its clean appearance,

this marble is a popular
countertop option

and these thin slabs will be shipped around
the world for use in luxury kitchens.

[Keith] We've just separated
about 60,000 lbs. of slabs right there.

Put wedges in there to make sure
they don't tip or slam back together.

When we brought this block
in, it weighed about 45,000 lbs.

Put it in the gang saw,
cut it into 393cm slabs,

made beautiful Ariko slabs. They
weigh about 1,100 lbs. apiece.

[narrator] All of the finishing
touches are done in this cavern

and the final stage is grinding
down the rough mine surfaces

and polishing the slabs
to a high shine.

They'll be brought from here
over and put on this auto loader,

set on and go on through
the polish line

and they'll be ready for sale.

[narrator] The advances
in technology and efficiency

here at Danby quarry
have allowed this operation

to continue producing this
coveted mineral for over a century

and the world's love
of marble hasn't slowed.

It is still the stone of choice
for any opulent building.

For these reasons,

the quarry is likely to survive
into the coming decades

or possibly centuries.

[narrator] Blanketed by the
rolling hill sides of Moldova,

lies an underground world
hidden from sight.

Within 75 miles
of winding tunnels and mazes,

250 ft. down,

these caves contain the
secret to the country's success.

[narrator]
Rich in history and geology,

this massive subterranean city

is unlike
any place in the world,

yet it would take decades
before this region

could distance itself
from the eastern block

and come into its own.

[narrator] How does
the region's unique geology

contribute to its thriving
wine production?

[narrator] What caused the
nation's most successful industry

to come
to the brink of disaster?

[narrator] And how did
Moldova's most flourishing product

make an epic comeback?

[narrator] Tucked away
between Romania and Ukraine,

is the nation of Moldova,

a country where over
25% of its population

is involved in wine production.

Rich soils and vine-covered
hills can be found at every turn

and its sunny slopes contain the
ideal conditions for growing grapes.

[narrator] But before Moldova was
known internationally for its wine,

it extracted another precious
commodity from the ground,

one that helped build
the country we see today.

[narrator] The land
in this region of Moldova

was formed 12 million years ago,

during the Miocene period,
when it was under the ocean.

A reef rich
with organisms thrived,

leaving behind deep
underground reserves of limestone.

[narrator]
Igo Nicoara is an expert

on the region's geology
and its mining history.

[narrator] With 75 miles
of underground tunnels

200 ft. below the ground,

the caves under Cricova were
created by centuries of mining.

[narrator] This method
of horizontal excavation,

creating galleries and rooms,

was invented in Moldova.

[Igo speaking]

[narrator] The method was used
because the best limestone

was at a certain depth,

a band, 60 ft. top to bottom.

[narrator] Thanks
to the tunnels left behind

by centuries
of limestone mining,

Moldova's wine industry was
able to grow exponentially.

Once the major producer
of wine for the Russians,

the country
was running out of room

to store their precious export.

Creative winemakers
ventured underground

into some abandoned
limestone mine tunnels

and found
the perfect environment

in which to store
their libations.

[narrator] Temperatures in
Cricova's subterranean network

stay consistently
in the mid-50s,

the perfect conditions
for wine aging and storage.

Natalia Salari is an expert
on the nation's wine industry.

[narrator] The science of wine aging
all comes down to where it's stored.

Storing wines
in humid conditions

helps prevent the cork
from drying out,

which could allow oxygen to
enter the bottle and oxidize the wine.

At the winery, over 7 million
gallons are stored in oak barrels.

[narrator] The chemical processes
that occur in the oak barrels

give the wine a fuller body
and more complex taste.

Yet the most remarkable
impact the oak barrels made

was during World War II.

It had nothing to do
with wine at all.

Jewish citizens
fearing for their lives

fled to the tunnels

and hid from the Nazis
inside the oak barrels.

Eventually, the tunnels came
to serve a livelier purpose

when in 1952 Stalin ordered
for five tasting halls

to be added to Cricova's
subterranean network.

During this time the site
became a key destination

for all official
delegations to the USSR.

They also received a visit from
the first man in space, Yuri Gagarin.

[narrator] Shockingly, the most
valuable collection currently stored here

belonged to Herman Goring,

commander in chief
of Hitler's air force.

[narrator] By the 1980s,

Moldova's wine industry surprisingly
fell victim to a country in crisis

when an unexpected
change in policy

turned the tide
for these skilled winemakers.

[narrator] In the mid-1980s,

Soviet President,
Mikhail Gorbachev,

attempted to curb alcohol abuse

by launching
a partial prohibition campaign

and it took a toll
on the winemakers of Moldova.

One-third of the vineyards
were forced to close.

[narrator] In 1991, Moldova
gained her independence.

And over the next two decades

wine production
began to grow again,

with Russia
still its major consumer,

but in 2006,
Russia issued an embargo

that sent the smaller country
into yet another crisis.

[narrator] With the embargo,

the wine industry in Moldova
had to rethink its game plan.

Losing Russia meant they
had to turn to other markets.

[narrator] Although
the embargo was lifted,

today Moldova
has future-proofed itself

and exports to 50 different
countries across Asia,

Western Europe,
and the Americas.

[narrator]
These cellars are best known

for the sparkling wines
they produce.

[Natalia speaking]

[narrator] The sparkling wine is made
using the French Champenoise method.

[narrator]
The base wine is then bottled

and a liquid solution
containing yeast and sugar

called
liquor de tourage is added.

[narrator] During fermentation,
sugar consumes all the yeast,

producing alcohol
and carbon dioxide

and bubbles are formed
inside the bottles.

The bottle are then
placed upside down

to ensure all the sediment gradually
accumulates in the neck of the bottle.

[narrator]
A team of workers rotate

as many as 35,000 bottles
of sparkling wine every day.

[narrator] The sediment
is then frozen to -16° F

and removed
in the disgorgement process.

The crown caps,
they would be just popped out

under the high pressure,

which exists already on
the bottle of sparkling wine.

[narrator] Now, Moldova's
wine industry is thriving

and the Cricova
cellars continue to grow.

At the far end of the caverns,

miners are still
extracting limestone,

which means more space
will be available

to utilize for winemaking
in the near future.