Imagine the underbelly of a big energetic city that's clearly on the move.

What would you expect to see just under your feet or even far below the surface?

Welcome to our world.

To most, it's an unknown world, dark, mysterious, and filled with secrets.

I'm amazed at the size of this tunnel.

This is enormous.

24 by 21.

Sometimes it's a world that can glitter.

How much would you give us as an assessed value for all the metals that you have in this facility?

I'm afraid I'm prohibited from sharing that information with you.

As they say, I could tell you but then I'd have to kill you.

And sometimes it bears witness to a more fearful time in our history.

Even though there's so much here, I wonder if it really would have done any good, considering a nuclear attack back at that time.

Well, it was very, very real, and I'm sure if nothing else, it would have been a temporary stop before you died.

It's a world where grand plans and dramatic gestures never saw the light of day.

And there were three other anchorages that are identical to this on the bridge.

All with the same intention to be used by the pedestrian walking across the bridge, using the public transportation system on the bridge that never actually was used.

A world where stalactites accumulate in man-made caverns, and where the city's grandest public building bears witness to the Victorian era in which it was born.

I'm Derek Pitts.

As an astronomer, I'm usually focused on the heavens, but today I'm turning my scientific attention toward an exploration of the unknown world beneath our feet and unlocking the secrets hidden there.

[music] Since 1926, the Benjamin Franklin Bridge has linked Philadelphia and Camden and has been one of the dominant sites on the Delaware Valley skyline.

Upon its completion, it was the longest suspension bridge in the world and was planned as a public transportation focal point for the region.

Joe, we're looking at a concrete footing and the anchorage for the cable on the Ben Franklin Bridge on the Philadelphia side this is.

And we can see here on this plan without too much trouble that there was originally planned to be a tunnel for the Frankfurt elevated line.

The bridge was really built for people who didn't own cars as much as for those who did because they owned cars back in the 1920s.

So they built a lot of pedestrian and public transportation options right into the bridge.

They incorporated that for pedestrians, for people who wanted to ride trolleys.

That was all built into the original concept of the bridge.

By 1926, there were more cars on the road and some of this never came to be, but it's kind of a view of how they saw the world right after World War I. What we know today is the Philadelphia Plaza was dug out and was originally supposed to be a major interchange for a trolley system.

How would people recognize this spot today?

The lightning bolt statue.

We'll go look at it.

That sounds great.

Let's do that.

Okay.

Well, Joe, I never imagined that a bridge could have a basement.

We can see the Patco line runs right underneath the bridge in the basement down here on this side.

This is going over toward New Jersey.

But as I look to see the train tracks coming back west from New Jersey, there's an enormous cavern here underneath the bridge.

It was originally going to be a trolley terminal underneath the Philadelphia Plaza of the Ben Franklin bridge.

But by the time they opened the bridge in 1926, the world had changed.

People didn't want to ride trolleys anymore.

Now they wanted to ride buses.

The tracks stayed there, but the trolleys never ran.

And this huge cavern under the Philly Plaza has never been used.

There would be a different kind of terminal appointments, a ticket booth, ticket office, things like that, right down here under the bridge.

It was going to be as busy place as originally planned.

Now it's this is sort of like a ghost town of a station down here now.

So we're also directly underneath, you said the Philly Plaza side, and directly above us is the... The Bolt of Lightning.

Did people see the, the, um, the Gucci statue?

Uh, the Bolt of Lightning is right there.

So as people go around the Plaza to either get on or off the Ben Franklin bridge, they're right above us now.

So now the next time I drive over the bridge, I'll be thinking about the terminal that was originally planned to be down here, but never ever opened.

As Joe and I walked around, I saw evidence of just how cave-like this long abandoned site had become.

This actually is a stalagmite and this would be a kind of a calcium spire that grows up from the ground in a cave when you have calcium deposits dripping onto the ground in one spot.

The water sort of slides off the top, but the calcium builds up and makes this little mound.

So where does the liquid come from?

Well, the liquid comes from all the way up top overhead.

You can see soda straw stalactites growing down from the ceiling.

The moisture that leaches through the deck of the bridge comes down through the concrete, forms the extra long soda straw thin pipe of calcium, and then it comes all the way down, drops off of that, and comes down and forms the stalagmite at the base.

Those distinctive stone towers of the bridge also have stories to tell, about transportation, and about how a bridge is held together.

They're just partially underground, but for a story like this, we'll stretch a point.

There's another place that was open, that was planned for public access, but was never opened.

In here.

Wow.

We're up at the walkway level.

If you wanted to walk across the bridge, you could come in here.

This was designed as a public area.

He put up these murals of all different types of transportation.

Steamboats, sailboats, early locomotives, what they call a flying machine, which was a stagecoach to our way of thinking.

And I can see here there's even a dirigible or a zeppelin on the wall as well as going back as early as 1492 with Christopher Columbus' Santa Maria.

It was designed to honor many different forms of transportation.

And there are three other anchorages that are identical to this on the bridge and all of them have the identical artwork.

All with the same intention to be used by the pedestrian walking across the bridge using the public transportation system on the bridge that never actually was used.

This is amazing.

This is the stone building that you see on the Camden side of the bridge.

There's another identical structure to this underneath the stone building on the Philadelphia side.

We call them anchorages because this is where the cable comes in and anchors around a big steel beam and the tension of those two beams is what holds the bridge up.

Now as I look out the window over here Joe I can actually see water through those windows.

So this chamber extends down how far?

It's several hundred feet under the under the water level and the footings go all the way down into the bedrock which is probably about a hundred and thirty feet down beneath the surface.

So even as we look down here and we see the floor of this chamber, that's not the end of this.

Not at all.

And remember, when this was built in the 1920s, basically the only way to dig this out was guys with picks and shovels.

This is what holds our bridge up.

Wow.

This is absolutely incredible.

I think the only thing I've ever seen that was anything near this spectacular is maybe the structure at Kennedy Space Center for the launch vehicles.

It's the only thing I've seen anything like this.

This is incredible.

So now, how many strands of cable are there down here?

There's about 16,000 strands in each cable.

There's two cables in each side of the bridge.

And there's about 26,000 miles of cable, of wire, when you put them all together.

They had a machine that would just take one strand at a time, go up and over the towers, back into the anchorage, wrap around, and then back over the towers.

One strand at a time.

One strand at a time.

To do all this work through here.

The beams that these are tied around here or roped around here, these are now connected to the concrete anchorage down beneath this.

Right.

And eventually all the weight gets transferred down into the bedrock underneath the bridge.

For all intents and purposes the cable is the bridge.

If the cable goes you don't have a solid bridge anymore.

So the integrity of these wires is extremely important to the long-term future of both this bridge and the Walt Whitman.

So if you keep the cables you keep the bridge.

That's correct.

For over 75 years the bridge has linked Pennsylvania and New Jersey.

And in that time the Market, Frankfurt and Broad Street lines have linked the neighborhoods of Philadelphia.

Each year passengers log over 1 million miles spread over 52 stations.

And late at night as the trains return to their terminals, SEPTA's maintenance crews come in to work in the tunnels to keep the tracks in working order.

Joe, it looks like they're drilling right here, but what's the work that's actually going on?

The drilling is done.

He's running down the spikes that hold the, this is a frog, it's a component that allows two rails to come together in a crossover move.

And he's just basically running down spikes to secure it to the tie.

So as the train comes along through this section, it can slide from one set of tracks over to the other set of tracks along this.

And this whole piece is going to be, is this in the process of being removed now or installed?

No, this is being installed.

This is a renewal, this is the new frog, and he's just tightening it down to the ties.

And so about how long is it going to take to put this piece in?

This piece won't take long, maybe a couple of hours, but the overall crossover will take anywhere from six to eight weeks.

Joe showed me how the so-called third rail generates power for subway cars on the Broad Street and Frankfurt lines.

The subway car is fitted with L-shaped metal connectors called shoes.

Four shoes extend from the bottom of the car, sliding on top of the rail as the car rolls by.

The electrified rail is on the bottom, with a wooden rail above to protect the workers.

Electricity is transferred from the rail, to the shoe, and into the car's motor, providing the necessary power.

It is an efficient energy source, but you definitely have to watch where you're walking.

At 600 volts, Joe, that's quite a lot of juice.

What would happen if a person actually did touch this?

Depending on if they were grounded or if they were attached to a return source, it could actually kill you.

There's plenty of voltage there to kill anyone.

In other cases you might just get a little shot.

We refer to them as a little bite.

Every now and then when we work around third rail, there have been people, myself included, that got a little bite.

So you get a little nip.

It's unpredictable.

If there's a little moisture, if your gloves are wet, or if it's raining, it's real good to stay clear of the third rail.

But Shirley, that must be scary to get that little bite.

Oh yeah, it lets you know you're alive for sure.

Farther south at the Pattison Avenue station, crews are actually replacing the entire system that anchors the track to the ground.

The old system had been in place for a quarter of a century.

They're replacing the old fixation system with new.

To do that, they have to jack the rail up, remove the old plates, reinstall the new plates, re-anchor it, drop the rail back down, and then clip it up.

So it's a process, but it is a noisy process.

This is a coring rig that drills the holes to set the anchors that hold the new fixations.

These are fed by hydraulics that run the motors and also a cooling system that washes out the debris from the coring itself.

So now what is it, when you actually drill down through this, what is then replacing the core that's been taken out?

The anchor that actually holds this in?

The hole is cored to place the new anchor in place.

This is the anchor.

It's about 5.5 inches deep.

And once it's cored and the holes are cleaned out and dried, we actually vacuum these holes out too.

This will be set into an epoxy and left overnight, at least 24 hours, to set up before we come back in and install the new plates.

To install the new plates, basically you unscrew the bolt and the anchor will be in the ground and then put the new plates in place and just screw the bolt right back in again.

So where we are right here we still have the old plates in on either side here the new plates going to go right in here.

That's correct wherever it's possible that's the best way we can get more productive work that way so wherever we can fit a new in between the old that's what we do.

So there's a lot of equipment in here there are the coring heads right here the skids that provide the hydraulic fluid in the water and then some sort of traction device to move all this stuff around.

Where do you store all this when you're done work for the night?

Well if you're interested we can take a ride about ten miles north from here right now.

Where I'm taking you Derek is the upstairs of the subway at Erie where you can actually store four or six car trains.

One on each track.

That's a lot of train.

Yeah this is the upstairs at Erie.

It even has a little balcony view.

Oh look at that.

Look over here you can see where the express track and the local tracks run.

Right down here below us.

Right below us.

This is amazing.

Joe how far up would you say we've come from Erie Avenue Station?

This is north of Erie toward Logan.

How far up have we come?

Probably around a thousand feet or equivalent to several football fields, 3-4 football fields to this point.

And we probably have another thousand feet you can go Where the trains would be stored or turn around.

I can't get away from thinking Joe that all the cars rolling along Broad Street, all the people walking back and forth between Broad and Erie and north toward Logan have no idea that this enormous storage space is down here.

If you didn't know it was here, you probably wouldn't even looking over the edge of the platform you'd never even recognize it or wouldn't notice it.

I noticed how clean the track bed was and Joe invited me to Olney Avenue to see how they do it.

So Joe, what is this enormous machine you brought me here to see?

This is what we refer to as a tunnel vacuum.

It's a huge vacuum run by turbines and a six-cylinder diesel engine, Detroit diesel, that vacuums basically the floor of the subways and all the drain basins in the subways as well.

So that thing goes up and down the track from all the way along the Broad Street line?

It's used all year long and does Broad Street and by the time it gets done one end it'll be probably three to four years and it'll be time to start all over again so it's an ongoing process.

So this has got to be about several thousand times more powerful than what we find at use in our home.

I couldn't even give you a comparison.

That's amazing.

So it'll pick up just about anything that's down here.

Any of the trash that's found down here.

Yes, pretty much trash.

Stones, if there's stones down here, small pieces of metal.

Now, so when does this take place?

That process takes place during the night when the trains are put to bed for night, or they go into the night alley, call it, where there's no longer a train service running.

Didn't know all that went on down here.

A lot of people don't.

Most people don't know it goes on.

When everybody else is home sleeping, these guys are down here cleaning the subways and building track work.

So the next time I'm coming home late from a movie and I'm driving over Broad Street, 1 o'clock, 2 o'clock in the morning, I'll think about what's going on down here.

Coming up, we'll tour the remains of the nation's pioneering waterworks, visit an electric substation hidden near a hallowed shrine, Kathy, are we there yet?

Not quite, Derek.

Learn how a great public fountain keeps pumping and take you into a place you'd never think of visiting but is vital to the way we all live and work.

Welcome to our world.

That's next on Secrets Beneath the Streets.

Coming down, Johnny.

This man is descending into one of Philadelphia's nearly 85,000 manholes.

It's not a glamorous job, but it's vital to our everyday lives.

How much sewer line is there in Philadelphia?

In Philadelphia we have over 2,900 miles of sewer throughout the city of Philadelphia.

Various sizes and shapes, different materials, concrete, brick, terracotta, and some made out of Belgian block.

We have combined sewers, we have separate system sewers, and we have sanitary source and storm source.

The sanitary source take all the waste from people's houses.

They just flush it.

They don't care where you go at.

But we do.

This sewer here stretches 14 miles across Philadelphia.

It runs from Mount Airy, parts of Germantown, comes across Broad Street, and runs through the Logan section, Feltonville.

One thing about this sewer, it runs underneath the subway.

There's not that many sewers that run underneath the Broad Street subway.

I didn't even bother to think about how the sewer line would be threaded through all the other stuff that's underground here.

Well now for us to be down here, since it's a combined sewer, we need to have some special gear.

Yes you do.

First of all we have to check the atmosphere down there.

We have meters that we check for oxygen, air, and explosives.

Make sure it's okay for us to breathe down there?

That's correct.

And make sure there's not going to be any other problems down there.

Yeah, we make sure there's no problems.

The only problem we can't prevent might be some rats.

Oh, well, we'll see what we can do about that.

We provide you with all the protective gear.

We give you body boots.

And then you wear a rain, sort of like a raincoat over that.

Gloves.

Gloves.

And a helmet.

Then we wear a helmet.

OK.

Reason why you need that raincoat, you don't know if somebody might flush it on you or not.

Welcome to our world.

As we said, this is a very large tunnel.

You said this tunnel, how big is this tunnel again, Richard?

21 by 24.

21 by 24.

Now, I never imagined that there could be a tunnel this large underneath the street.

Well, this is the biggest one in the city that I know of right now, and I'm almost sure this is the biggest one.

But this is fed by a lot of other pipes coming in from different directions.

So what do we have here now, Richard?

Now this is a sewer coming up Huntington, coming down Huntington Park right here.

Alright, so whatever goes down that sewer drains right out through here?

Right through there.

Okay, and this would be the storm runoff?

Well this is probably a combination too, but that's probably somebody's storm drain.

That's where it comes out at, right there.

Alright.

This is another sewer on Huntington Park.

Now about how big is that in diameter?

This is a 25/30.

A 25/30.

Right.

Do you ever have a need to get up into a pipe like this?

Yes.

Yes.

How would you get up in there?

Crawl.

He crawls in this type.

You would crawl right up into that pipe.

Right.

Send the guy down to do the inspection first.

Right.

Check out what the situation is.

And if he can handle it by unblocking it, he'll take care of it.

If not, we have machines that we will send in there.

We also have TV cameras that we send in.

You do.

Yes, we do.

Richard, is this mostly brick construction, concrete construction, brick and concrete?

OK, we have Belgian blocks.

And is that what the surface is underneath our feet?

The Belgian block?

Right.

That's what I can feel down here.

OK.

Amongst other things.

I see.

Well, right now the water is not not too deep.

It's only about what, two feet here maybe?

Well, this is all sanitary flow here.

Take a look in that water, man.

Tell me what you see.

See how murky it is?

Yeah.

What you think you see is what it really is.

What it really is.

Uh-huh.

Oh, I see.

This is sanitary flow.

I understand.

Those floating pieces are floating pieces.

Yes, they are.

I understand that.

And this is coming from a long way.

This one right here, that's a lateral, and that would be coming from a residence in this neighborhood.

Right.

So any kind of wastewater would come out of that and come right down into here.

And we can see how there has been some flow here at some time.

And you really don't want to stand here too long, just in case.

Let's keep moving.

Let's keep moving.

This water is headed towards the plant, Northeast Silt Treatment Plant at 3900 Richmond Street.

Part of this water goes to the plant, the other part goes into the creek.

So this eventually, some of this eventually gets to the Delaware.

Right.

The rest of this all goes to that Northeast Water Treatment Plant.

It gets recycled there, comes back into the main water system that serves all the residences in the building.

Now, when it rains, how full does this get?

Follow me, I'll show you.

You see that debris on that ladder bar?

Last week during all that rain, that's how high the water was.

But that means that this tunnel is more than half filled with water.

Yes.

21 by 24.

Correct.

That's 12, 13, 14 feet of water in here.

Yes it is.

So now I understand why this has to be so big because when the storm runoff comes into the system and it all feeds into this, it's got to have some way to go.

In all the cities around the nation, how does the Philadelphia sewer system rate among all the other systems around?

Number one.

Number one.

Number one.

Number one.

Now how did I know I should expect that answer?

[laughter] Okay.

Our way back out is this way?

Can we come this way?

Yeah.

You sure?

Yeah.

Well, let's see if he know the way out.

Oh, okay.

I know the way.

Philadelphia has a long history of leadership in the treatment of its water.

The Fairmount Waterworks at the Schuylkill River has been a Philadelphia landmark for nearly 200 years, immortalized by artists, visited by luminaries.

But what appears to be a sort of Greek temple was built for the most basic of reasons, to ensure the purity of the city's water supply.

But how did it all work?

That's where the secret comes in.

Well, the secret, Derek, is that the buildings you see behind you are pretty much decorative.

They're not the heart of the waterworks.

The waterworks, the heart, what made it this site that provided water to the city is down below.

This was an extension of the engine house, intakes for the pumps down there, water source behind you.

What you're in is essentially the oldest part of the waterworks.

This is the engine room.

This is the whole reason the waterworks was built.

Because Center Square at City Hall was not able to provide enough water to the city, we were looking for a fresher, more expansive source of water further up the Schuylkill.

So we built here, but we weren't willing to give up the steam engine technology.

But instead of one steam engine like they had at Center Square, we put in two.

And they represented the third and fourth steam engines built in the United States.

And you need to imagine them going up through the ceiling almost for the full height of the building.

That's three stories tall.

So the boilers were on this side of the wall.

They provided the steam that drove these engines over here that then pumped the water.

Exactly and that's what you see over here.

This represents a force main sucking water directly out of the river causing a pump to suck the water up and take it 96 feet up to the reservoir which stands where the Art Museum now stands.

Okay.

So our Art Museum originally was a reservoir and how much capacity was there?

About a million gallons.

Another reason for having water sit in a reservoir at such a high location is that the water can settle.

But the city was growing, it was not enough to handle and it was too expensive to run.

Is there a cheaper source of power?

So what did they do?

They looked to the river.

Cheaper source of power.

The steam engine room functioned primarily between 1815 and 1820.

But as I said we were changing our technology.

One could argue we were backing up a little bit but the truth of the matter is with steam engines so expensive we needed to find something else and water wheels is where we decided to go we had the precedent in mills we had the precedent for using water power to get what we needed to have done done this space represents a water wheel and I want you to take a second to look behind you it filled this room rows of buckets that will carry water we took chances with technology we were innovative and we were also among the first cities if not the first major municipal city to provide water to its people and we tried different ways of doing it steam engines were good water wheels worked for us better and I understand there's one last step in this process yeah there is another step what they found was that because the Schuylkill is a tidal river that twice a day the wheels would stop and you can't provide water when the wheels aren't moving so what did they do well here in Philadelphia we look to technology and in 1851 we took the radical step of experimenting with a Johnville turbine now Gail this technology that's here at that time was a new technology?

absolutely this Johnville turbine was put in place here in 1851 purely as an experiment we're still using water wheels to provide the city with its water but we're trying to figure out a better way to do it and this system is what they came up with.

there's a obviously an awful lot of water pouring through the system is there any danger that this could break down in any way?

well absolutely the way they built the gears were that the smaller gears were cast iron because they're more expensive to cast but the large wheels have wooden teeth so that if something gets stuck in the gear if the gear gets a little bit out of alignment and one of those teeth should break you don't have to cast the whole wheel again the whole gear all you have to do is replace the tooth at the time there were seven in place on site feeding the reservoirs up top but this 1851 the experimental model ran from 1851 till 1909 were there other facilities like this in the United States not a one so what happened to the site people came to see it it became a tourist destination people we now consider famous Charles Dickens Mark Twain came here to look at the technology to see the man-made lakes that were the reservoirs and just wonder at the skill of man in harnessing something called technology.

By the turn of the 20th century the Fairmount Waterworks had become obsolete but the site clung stubbornly to life.

In 1911 the nation's fourth aquarium opened to educate the public about marine life.

It was replaced by the short-lived aquarama in the 1960s.

Then the famous Kelly family came to the rescue with an Olympic-sized pool for athletes and the public alike.

In 1972, the pool was swamped by Hurricane Agnes, never to open again.

The Water Works is preparing for a new life as the Fairmount Water Works Interpretive Center.

And now we're going to go to another familiar place where we'll see some unfamiliar sites.

Here we are at Independence Mall, part of the most historic square mile in America.

But did you know there's a secret beneath the streets here?

Well the secret is you're standing next to PECO Energy's underground substation.

Mall sub located right in historic Philadelphia.

Right here?

Right here.

How far down is it?

Goes about three to four stories down and it services electricity for the city of Philadelphia and it acts as one of our substations for our entire region.

But how did it get to be here?

Well it got to be here there was in the mid-1960s Franklin substation was located above ground in Old City and when they began construction of the federal building our substation had to be moved so we decided we'd do something no one else had done before and took it underground.

So now that's a big deal to have it underground because there are lots of other substations but they're all above ground.

That's correct.

Wow.

Completed in 1966 PECO's Mall substation is one of the largest underground electrical facilities anywhere and feeds electricity to over 1,500 center city businesses.

Kathy are we there yet?

Not quite Derek.

Golly.

Ah, so we're getting there.

We are.

You have arrived.

Finally.

Welcome to Mall Sub.

Wow.

Derek, now that we're down here I'm going to introduce you to Vince McAleer.

Vince is a foreman with EcoEnergy's transmission and substations and he's really in charge I'm here with Vince, a foreman with PECO Energy's transmission and substations.

He's really in charge of most of the place.

I'm going to turn it over to Vince.

Good morning Vince.

Good morning Derek, nice to meet you.

Let me show you around the substation.

Great, let's take a look.

So Vince, what do we have down here now?

Derek, this is a substation.

What we have here, we have 13,000 volts coming in.

It goes to a transformer and we break it down to 2,400 volts.

and that goes out to the distribution circuits and feeds our center city network.

Well tell me Vince, how many people work down here?

Nobody works down here, this is all automatic substations.

Is it really?

Yes it is.

How many of these 13,000 volt lines do you have coming in here?

We have four 13,000 volt lines coming in from Delaware Generating Station.

And we have about 30 outgoing lines going out to the network.

The substation is about 275 feet long and it's about 90 feet wide.

So that's about the size of a football field all underground here.

So Vince, now the power comes across on these cables over the top, ends up at these boxes here, and then gets distributed on this wall?

That's exactly right.

They come up here and this is where they go out into the network.

They leave the pod heads right here, come up here through the ducts, and out through the ducts to the streets.

So this wall, though, seems to be just a conduit wall.

It's just open tubes all the way up from floor to ceiling.

Exactly.

That wall was made instead of bricks, we had ducts in there.

And each one is a hollow brick that we can put our cables through.

And from here, this cable now goes out to where?

Out to our network in the street all through Center City.

So this is now what's underground below the manholes, below the street, these cables that go out and distribute the power around.

Exactly.

Interestingly enough, this wall is almost artistic.

It's almost as if somebody decided they needed a little bit of wall decoration in here and this terracotta piping certainly fits the bill and serves the purpose of distributing the electricity at the same time.

Yes it does.

This is a blower motor that cools down our transformer.

Like I say, our transformers here are air cooled.

This is the motor, this is the blower.

The air comes in from upstairs, comes down through the shaft and up through our transformer and back out to the street.

So if I'm ever out on the street, I might feel this and wonder, "Gosh, where's this warm air coming from?

It might be from here."

"Exactly."

So the next time you're walking through Independence Mall, remember the secret that's just under your feet.

The Swan Memorial Fountain on the Benjamin Franklin Parkway is one of the nation's great public fountains.

The bronze figures were designed by Alexander Sterling Colner.

The three human figures represent the Wissahickon Creek and the Schuylkill and Delaware Rivers.

But just how do they keep all of that water cascading over the parkway?

To find out, Mike DeSanto of the Fairmount Park Commission took me for a tour of the underground workings of the fountain.

Derek, welcome to Logan's Pump Room.

Mike, this is a fascinating place.

All these pipes have run all through the complex here.

This is almost an engineering marvel down here, it looks like.

Mike, how much water is in this system?

This fountain holds approximately 100,000 gallons of water.

And is that all the water you use for the whole season that it's on?

No, we have a filter system that prolongs the life of the water for about two weeks.

So every two weeks we drain it, clean it, and then refill it.

Now this is sort of an octagonal room down here, and I notice there are a number of tunnels going off from the central point here.

Why do we have those corridors?

What do they carry?

With this system we can access the piping and the lighting at any particular time to do our maintenance.

As you can see there's 12 tunnels, and even myself working down here over a number of years, I get turned around.

So what we do, if you look, we have yellow stripes by the two exits.

Right, that's a great idea.

I can't tell which tunnel is which.

This pump setup right here is the pump setup for the turtles and for the frogs.

Correct.

It's a 15 horsepower pump and it supplies about 800 gallons of water for the turtles.

If you see the dripping, that's not a leak.

We have to supply water to the bearings to keep them cool and lubricated so the pump works correctly.

So how long does this pump operate during the day?

About 20 hours a day.

And is that true for all the pumps down here?

Yes.

You know Mike, it's amazing in this room how much piping there is.

For the amount of piping and the amount of water that's in the room here, I'm surprised that the floor is so dry.

Every once in a while there's a drip here and there, but it's pretty well sealed up here.

It's very important that we keep the area dry when you're looking at a hundred thousand gallons of water above your head.

I suppose you wouldn't have boots high enough to keep you dry if there was a big leak down here.

No.

I'm glad we have that exit sign to let us know which way to get out.

Mike this has been a really great tour, but one thing I'd love to know is how difficult is it to turn the system on and off?

Very difficult, Derek.

See this switch right here?

You turn it off.

That's it?

That's it.

[MUSIC PLAYING] So Mike, if it was that easy to turn it off, can you turn it back on the same way?

Absolutely.

[music] Stay tuned for more Secrets Beneath the Streets.

Featuring a look at a local version of Fort Knox.

How many people actually get to see this room?

You're a rarity in that we allow very few people access to the depository facilities.

And the Victorian world that still exists in the basement of Philadelphia's City Hall.

This is like the Roman catacombs here, George.

It looks like it's something straight out of the Roman underground.

It's pretty neat, isn't it?

For decades, Fort Knox in Kentucky has been the official U.S.

government depository, home to a king's ransom in gold.

But you may not be aware that there are a few commercial precious metal depositories scattered around the country, too.

One of them is hidden beneath the streets right here in Wilmington, Delaware.

The folks who run it allowed us to take a tour, but they won't let us tell you where it's located.

All right, so where are we now, Mike?

Well, right now we're in the intermediary security area of our facility.

It's a sort of a transition area that introduces us to the high security vault, which we'll see in a minute.

I really love this great jacket you've given me.

It makes a wonderful fashion statement for me.

But I notice that I can't get into the pockets.

Is there a reason for this?

Well, there definitely is a reason.

When we have visitors such as yourselves come to the facility, which is not very frequent, so you're in a class by yourself, so to speak, we require visitors to wear these smocks, which are pocketless by design.

So that means nothing can be pocketed.

Correct.

So Mike, what do we have here now?

In this particular area, we have a variety of silver investment products that we hold for customers from all over the country and perhaps all over the world.

This is more silver in one place than I've ever seen anywhere.

Well, it's quite a bit.

For example, we have 100 ounce silver bars, which is the majority of the ingots that we see here stacked on these pallets.

They're manufactured by a variety of different companies, and that's why they sometimes appear to be in different form.

And that's about seven pounds of pure silver right there.

Correct.

That particular bar at today's price is worth about $450.

These are the pre-1965 US silver coinage.

Typically they're four thousand quarters, ten thousand dimes, two thousand, half dollars.

The reason they're bagged and the reason they're held in a silver depository is because they're now bought and sold for the silver they contain, as opposed to their face value as coinage.

More value than as the silver.

Correct.

As a matter of fact, that bag of thousand dollars trades in the marketplace for its silver content at about $3,300 today.

Wow.

You keep a very, very tight control over what comes into this room and what goes out of this room.

Precisely.

We have a redundant and a multitude of physical security measures, alarm systems, monitoring capabilities that really renders our facility and our operations state of the art in that respect.

Mike, here's what I think, what I would consider to be the mother load of silver.

I haven't, again I haven't seen this much silver, especially in one piece.

What do we have here?

Well these bars are commonly referred to as thousand ounce silver bars and they're the form in which silver is generally produced for industrial consumption.

Each one of these bars bears four markings that renders it as unique as a fingerprint.

It would have a serial number assigned by the manufacturer.

It would have a finest designating in this case this bar is three nines or ninety nine point nine percent pure.

And then it would have a weight in this case it's exactly one thousand ounces.

Just trying to heft one of these.

If it's a thousand ounces this this has got to be what?

It weighs about seventy pounds.

Wow.

Talk about doing curls with something.

By the time I get done with this series, I'll look like Arnold Schwarzenegger.

That is a massive piece.

Well, Mike, I can tell you this is my favorite room in the building.

I feel really special in this room because we're surrounded with so much gold.

Yeah, this is, as we said earlier, we're in the high value vault.

And this is the area where we store our customers' gold.

What we're looking at here are 100 ounce gold bars and 400 ounce gold bars, the two largest forms of investment gold that are manufactured today.

Well, I'm going to bend right down over here and pick up one of these big bars.

Oh, I can just barely do it with two hands.

This is really a beautiful piece of metal.

As I said, it's a 400 ounce gold bar.

It bears the same markings that the large silver bar had that we were looking at earlier.

This one happens to be pure gold, 99.99% pure.

It weighs about 28 pounds, and it's valued at today's gold price just over $100,000.

Mike, I see some other materials over here that are not gold.

In fact, they don't look like they really belong in this special materials room.

What do we have here?

Well, the bars you're looking at here are actually platinum bars.

And quite the contrary, they are very special for a variety of reasons.

Platinum is more valuable in the marketplace than is gold today.

It's primarily an industrial metal.

It's rarer than gold.

It's used widely throughout the world as a catalytic converter, particularly given its rarity is extremely high right now.

And it tends to drive the price high.

But Mike, this piece that I'm holding in my hands right now, this doesn't look like very much.

This looks like a piece of scrap metal that I have at home in my basement.

But what do you think, what would you assess this at?

What value would you say this is?

Well, this particular piece is 50 troy ounces and Platinum Today sells at over $600 an ounce.

So that's well over $30,000 in value.

This piece is $30,000?

It is indeed.

What would you give us as an assessed value for all the metals that you have in this facility?

I'm afraid I'm prohibited from sharing that information with you.

As they say, I could tell you but then I'd have to kill you.

Well in that case I think we'll just let it go.

Precious metals aren't the only things to be found in underground vaults.

You can also find a bit of America's recent history.

[Explosion sounds] ♪ Lert the turtle was very alert.

When danger threatened ♪ him he never got hurt he knew just what to do.

He'd duck and cover duck and cover.

You and I don't have shells to crawl into like Bert the turtle, so we have to cover up in our own way.

First you duck, and then you cover.

It wasn't very long ago that America lived in fear that at any moment the bomb would reduce us all to cinders.

Duck and cover In those days, Philadelphia was ready for the bomb with its own civil defense plan, complete with all the supplies a beleaguered city could need to survive a nuclear winter.

And in rooms adjoining the Broad Street subway, those supplies can still be found 40 years later.

It's one of the civil defense rooms here.

This is one of our rooms in the basement that we had storage civil defense supplies primarily water storage and medical supplies were stored in this room.

Jumps are all empty now.

They're all empty now.

Yeah I see okay and as you said there's medical supplies in here.

Yes right here it has kaopectate eye drops.

There's something right here look at this this is sodium chloride table salt.

That's correct.

And you know after all I guess we are talking about 40 years ago because on this bottle of aspirin here the date is November 1962 and that would have been one month after the Cuban Missile Crisis.

That's correct.

I could remember because I was a young man of my 30s at the time.

It was absolutely most frightening time in my lifetime even though I was in World War II.

The threat of nuclear war was very very real and the whole country was in a state of panic at that particular time.

We're in a concourse underground on Broad Street north of City Hall going past Arch Street and on up to Cherry Street.

Yeah.

This is that corridor that's not used anymore.

That's correct.

And this material is here.

Was this the only repository for material like this or are there other places around the city?

There are a lot of places around the city that were civil defense storage depots.

This was this particular area that I don't know how many hundred people would design to take care of for a short period of time.

It was not a long duration period supplies.

Back in the 1960s we went up to a place up at 9200 Bustleton Avenue and we spent three days totally immersed in the civil defense atmosphere.

We had these portable toilets set up with screens in between for ladies and men's room and everybody had to live on the supplies of the civil defense.

Like a training course in case something happened.

That's right.

We were to go in and take over.

You know what to do.

Yeah, take care of people.

Well, that's what it looked like and I can see it's got that distinctive shape there that sort of gives a hint as to what it is.

It had a plastic back liner and it had a chemical.

Plastic liner?

Chemicals to throw in after to deodorant.

Oh I see and I can see some of that right down in there.

It looks like there's a deodorant pack.

There's a deodorant pack right there.

Now this is the other room we were talking about.

Again there's a huge quantity of water cans.

We have also crackers, medical supplies and candy in here.

Incredible.

Actually now here's one of the cans of biscuits.

Wow.

They don't smell exactly the same.

They're still edible.

They're still probably edible.

Where's the peanut butter?

Did you bring the peanut butter?

We forgot to bring a little with us.

Forget it then, we're not going to eat these.

How old are these crackers?

These are 40-50 years old.

Wow.

So these were stored in here with the other stuff probably in the late 50s early 60s.

I would not hesitate if an emergency to eat them today.

Even without the peanut butter.

Well, I guess if you have to eat something.

To survive.

Yeah, of course.

But this is just an indication of what kind of supplies are still around here.

That's right.

Well, now look at this.

I guess there was some reading material too, because this looks like it's a really old comic book here.

It sure is.

Gosh, I wonder if it's worth anything.

Well, we can't tell.

It's pretty messed up here.

But all the supplies look like they're down here.

You know, John, one of the things that comes to mind looking at all these supplies here and thinking about the era in which this stuff was placed here is that even though there's so much here, I wonder if it really would have done any good considering a nuclear attack back at that time.

Well, it was very, very real and I'm sure if nothing else, it would have been a temporary stop before you died.

If they attacked you with a nuclear bomb.

You know, it's probably a good thing and we should all consider ourselves fortunate that we never had to find out.

That's correct.

Duck and cover.

Duck and cover.

Duck and cover.

Two blocks south and another era in time stands one of Philadelphia's most familiar sights, City Hall.

It officially opened in 1901, but the foundations of the building were laid 30 years earlier.

Today, the basement of City Hall, extending under the entire four acre site of the building, is a time capsule of Victorian Philadelphia.

This is the old Dynamo room here.

As you can see, they spent a lot of time here.

What happened?

What went on in this room, George?

This is where they generated most of the power, some of the electricity, some of your heating.

One of the things I see that's really interesting about this room, George, is that it's not like a standard basement room.

And even the columns seem to have some design element to them where the flanges come out around the sides and they sort of pinch together.

If we take a look at this one right behind us over here, we can see how these columns come out and they're riveted, but it has this nice flange on the end.

And you'll find that throughout the building.

And this is just as articulate as the old Dynamo room.

It's awfully noisy in here.

Well, that's because we have a lot of compressors going right now.

And also one of the main boilers are here to heat up the hot water, the domestic hot water.

Besides all this fabulous mechanical works here, this is really stunning work that reflects a very high level of craftsmanship back at that time.

As you look around up above, we can see this gorgeous cast iron structural work all around the periphery of the room.

You look at the beams, these arch beams that they have going across here, coming off the top part of the apron, how intricate they are cut out with the designs and everything in here.

We don't have that anymore.

What you have in new construction today, you just have a piece of i-beam that's going across there.

It almost looks to me, it's very reminiscent of this being like a church almost.

This kind of very high arch work with the polished glazed tile.

Now this is stuff that people just won't get a chance to see.

The everyday city dweller will not get to see this.

Only the folks that work here in the basement get to see this gorgeous work.

And I think they take that for granted.

I mean, you just come into the building and you do your job.

I mean, just to look around.

But to take in this, this is just magnificent the way they built this building.

Oh, George, this is some room.

It's been about 15 years since I've been in this room.

This is the steam generator that's in this part of the, came from part of the Dynamo room.

This is an incredible piece of equipment here.

It's, it looks like it's about 10, 12 feet long and about three feet wide.

It's got all these big pipes coming off the sides of it.

It looks like this hasn't been used in a really long time.

Derek, as you can see, this, this is part of the turret and the foundation you carry it and it works its way all the way around.

So this is really the base of the tower that goes up in the courtyard.

Yes, it is.

Wow.

And also, if you look closely, you'll see the ornate tile that goes here and this is a circular.

and it's a circular staircase that goes all the way up to the seventh level hasn't been used in years we used to bring the prisoners in here and take them up to the holding cells that were up on the seventh floor and right now it's been abandoned and it's been taken over by police evidence and as you can see Derek look back in here and I assume Wow that what they have here is back in here is the underside or beneath the courtyard this is really an amazing believe that at one point in time that's where the coal was delivered and here is the underground area that I was referring to the passageway right in here Wow take a look in here where does this come George just take a look down in there and there's a passageway that runs all the way down underneath the floor that we were just looking at oh my goodness any idea where that goes George not at all this is truly stupendous you know I never imagined that there was any kind of construction like this underneath City Hall So George what is this enormous device this is what they used in the 1900s to test it the strength of the concrete when they poured concrete maybe it was for this building when it was being built or any any public building in the city and what they would do is they would pour it in this canister Wow and the concrete would harden and then they would put it in this machine to check the strength so they could pour concrete in this and that would be this piston would then be driven by the rest of this machinery exactly so that the operators could figure out how much stress it would take to make that concrete shaft start to buckle or break right okay and you would use this weight that's on this to sort of act as the scale for how much pressure you're gonna put on this this shows that they could put a pressure on here of 300,000 pounds per square inch would you imagine yeah mm-hmm I've been here for a long time but this this room is I don't know where it leads to well let's take a look and see what is that look at that shaft that goes to nowhere look how far up that goes I can't even see the end of it it may go to the roof Wow well if you give me a little light I'll I'll head up and see what I can see this triangular shaped sort of chimney I cannot see the end of it at all right out of sight at one point in time it could have been a trash chute this is truly behind the walls of City Hall I would have never imagined there'd be anything like this in this building either.

This is one of our old records rooms.

That's quite a door George.

Wow.

Boy, that's quite a room.

This is like a labyrinth down here.

There are so many directions in which this goes.

What's in here?

Well, there's some wills in here, some testimony, and in fact, there's something right here.

You'll have to look at that.

My glasses are... That's okay.

This is to the Register of Wills, June the 28th, 1866.

That's incredible.

It looks like it's a record for a tax of $147.

Look at the size of this book, huh?

Wow, look at the way... That's amazing.

So neat.

Everything's so neat and clean.

So well done.

Beautiful penmanship.

And look, right up here at the top it says, "For this gentleman, the care of a burial plot, just $5."

It's amazing that all this is still here.

And you know, actually, it's in surprisingly good shape.

Yes.

Even though it's been here.

I guess in this space, this space is nice and dry.

It's certainly, it's not wet at all.

Very low humidity, the temperature is fairly well controlled.

So, in fact, this is... Helps preserve.

In a sense, a good preservation spot for it down here.

With the tour of City Hall, our journey through the subterranean world is complete and it's one I won't soon forget.

Clues ranging from the tip of a ladder emerging from a manhole to the remains of a gigantic 19th century engine have revealed the vast infrastructure as well as the great history of this region.

I've seen sights I never imagined I would.

And not only that, it's been a lot of fun.

This is Derek Pitts.

So how far do we have to walk now to get out of here?

I thought you knew everything!

[laughing] [theme music]