Cities Of The Underworld: Revealing San Francisco's DARK Secrets (S3, E10) | Full Episode

[music playing] DON WILDMAN: San Francisco, California is full of deadly surprises. We're anticipating up to a 7. 9 earthquake in the next 30 years.

DON WILDMAN: From a former nuclear arsenal-- World War III has just begun. DON WILDMAN: --to the dark tunnels of a Wild West Underground Railroad. You know, these are tight spaces for little kids, not for me.

We'll discover how the war between the North and South reached the dungeons of Alcatraz. I'm in a tunnel beneath Alcatraz. And for the first time ever turn our cameras over to extreme urban explorers.

We're trying to stay perfectly quiet. We're in search of adventure on "Cities of the Underworld: San Francisco, Under the Rock. " [music playing] Hey, I'm Don Wildman.

I'm in San Francisco, California, a city perched on the edge of destruction since the day it was founded. It's known as a Mecca of hippies, artists, and start up millionaires. But if you dig a little deeper, you'll find the city has a dark side; Civil War fortresses, World War II strongholds, and top secret nuclear missile sites that defended the city for over a century from invaders.

San Francisco, California is surrounded on three sides by the Pacific. Over the years, its harbor has been the city's highway to wealth, a deadly threat and a savage gatekeeper. There's no more infamous prison in the world than Alcatraz.

For decades, it caged America's most dangerous criminals. But its reputation as an end of the road maximum security penitentiary is only part of the story. Beneath the cell block that housed the likes of Al Capone and Machine Gun Kelly are the brick remains of an old Civil War fortress, one that protected the Union's vast wealth and defended the Bay from foreign invaders.

Rich? - Yes. Hey, Don Wildman.

Morning, Don, welcome. Morning. I took a boat ride to Alcatraz with National Park Ranger, Rich Wiedman, to learn how the rock protected San Francisco from Confederate gunboats.

A mile and a quarter from downtown San Francisco, Alcatraz is a 22 acre island made of solid stone, an ideal natural prison. The water's 300 feet deep. OK.

The water temperature 48 to 52 degrees Fahrenheit. And so if somebody tries to escape, they can last in the water maybe 20 minutes before hypothermia sets in. 70% of the fish in the Bay are sharks.

So if you died from the cold water, you drowned, it's likely your body would have been gotten by the sharks. Nice! Where the hulking, concrete prison now stands, there was once a fortress.

Completed in 1859 and loaded with guns, its mission was protecting the millions of dollars in gold rush treasure, first from foreign enemies and then when the Civil War broke out from a Confederate army desperate to finance their failing war. 75 years later, when Alcatraz became a federal prison, the gangsters penned up here had no idea that a Civil War superfortress was right beneath their feet. No kidding.

Look at that. The main cell block on Alcatraz, B and C, the two cell blocks, 303 men at the highest, 336 cells. A fairly small sized prison for the worst of the worst.

Yes, it was the end of the line. You can almost think of it as isolation for the entire federal prison system was here on Alcatraz. And right across the Bay, how close to freedom they are.

They could actually hear the cable car bells from San Francisco, smell the Ghirardelli chocolate and the Hills Brothers coffee. OK, Don, we're going to go into an area visitors don't go. It's secured off with one of the original federal prison locks.

Grab a hard hat. We're going to go downstairs. So look at this.

We're going under Alcatraz into the dungeons of what was once one of the most important fortresses in the country. [music playing] So we're back in a Civil War here, right? Yeah, this area down here, Don, was 1857 onward.

We are standing in a dry moat. This is the outside of the moat basically right here. DON WILDMAN: The original fort was a citadel three stories tall with 104 cannons, a dry moat surrounding it, and two drawbridges.

The first two floors were ringed with narrow, rifle slit windows. 433 soldiers were quartered on the grounds. And the basement of the guardhouse doubled as a lockup for dozens of Confederate prisoners of war.

This is where the last area of defense was. If somebody attacked Alcatraz, got onto the island, got through all the cannons to get up here, you still have one last area of defense. You could basically last in this building with food and water upwards of a couple of months if you needed to.

DON WILDMAN: These defenses weren't overkill. San Francisco and its massive gold reserve valued at tens of millions today was a tempting target for a cash-strapped Confederate army. There's enough gold coming out of the Sierra Nevadas every two or three days that could have funded the entire Civil War.

So there was a fear that the South would attack the Bay Area. Was that ever proven that they had that kind of plan? Well, there was a ship a few days outside the Golden Gate that was getting ready to attack San Francisco when the Civil War actually ended.

So the threat was definitely there. Down here, you're in the Civil War, basically. They left the foundation and built the famous prison on top of it.

After the war, the fort was converted into first, a military and then a federal prison. The old brick structure was demoed down to the first floor then replaced with steel-reinforced concrete. These hyper secure areas 11 feet below ground remain and mutated into the dreaded isolation cells known as the holes.

Initially, these rooms were built as powder magazines for the citadel. OK. But when this became a federal prison in 1934, these four areas had bars put on them.

And this was the dungeon area. Wow. These were the original cells.

They were down here in darkness up to 24 hours a day. But remember, this was the end of the end of the line for the whole prison system. Right.

Screw up, you get on Alcatraz. Screw up on Alcatraz, you end up down here. Right.

From Civil War era prisoners to 1930s gangsters, there were over 14 doomed escape attempts by men so close to freedom, they could almost taste it. Look at that. This is some sort of drainage tunnel, probably a sewer or something like that.

You can smell the sea air coming in there. It must connect outside. So this must go straight out.

And I'm thinking if I was a prisoner stuck in this, down in the hole, if I dug right through here, maybe this is my escape from Alcatraz. But I've got it much easier than any desperate prisoner trying to escape. I've got my SWAT kit.

Now, just so you get an idea of how tight this really is. Just so you understand, I'm in the pitch dark here. And if I wasn't, I would have a better sense of how tight this place really is and a lot more claustrophobic.

But I can't see anything. So it doesn't matter. Only you can on this infrared camera.

How cool is that? OK, so I've reached the end of this tunnel. It comes down about 100 feet.

And right above my head, only five feet up, is a manhole. So that's daylight looking out there. All right, so basically, there's a storm drain, a sewage drain, for the old fortifications directly beneath Alcatraz.

I'm in a tunnel beneath Alcatraz, how weird. If I'd been a prisoner up there, man, I wish I knew about this. [music playing] [music playing] I'm on Hawk Hill in the Marin Headlands.

Since the days of the Spanish, this area was vital to the defense of San Francisco. And you can see why. There's the Golden Gate Bridge, San Francisco Bay.

These hills are laced with military infrastructure of every era. And I'm meeting with park ranger, John Porter. He's going to explain to me how San Francisco's defenses adapted to the nuclear age.

John? - Hey, Don. How you doing?

DON WILDMAN: John was taking me to a former World War II defensive structure turned nuclear missile site. It's a piece of San Francisco's underground that could have sparked World War III, and almost did. So imagine, I mean, this whole place was basically ultra tight high security.

You can now see in here if you're driving by. But this would have been guarded with attack dogs, military guards everywhere. You couldn't get in this place.

The year was 1951. The Soviet Union and China entered a deadly arms race. The US had to act fast, fortifying all its major cities, including San Francisco.

Nike missile sites were the ultimate anti-aircraft defense systems. Their sole purpose was to identify incoming aircraft formations bearing nuclear weapons and obliterate them with nuclear warheads before they reached their target. And for 20 years, this secret site in San Francisco was ready to do just that.

So what is all this here? Well, this is the radars. There were five radars.

And they were up on top of Wolf Ridge. And these are the battery control vans, the computers. DON WILDMAN: If Russian or Chinese planes were detected by radar, the computers would then guide the nuclear warheads 28 miles into the air, exploding the bombers and their deadly nuclear payload.

So this is where they ran the show? Yeah, there's the computer's right there. DON WILDMAN: The technology may look primitive.

But it was good enough to incinerate the world. Once, God forbid, there was an attack, what happens in here? Well, first thing they do is push this button, the siren button.

Yeah. You'd be calling all your your soldiers to your stations. Wow.

That would be a terrifying moment. DON WILDMAN: Nike missile sites were America's answer to a growing threat. But perhaps an even greater threat was storing 10,000 pound nuclear missiles less than 10 miles from a major metropolis.

One false move and San Francisco, the state of California, and most of the Western seaboard would be history. The nuclear arsenal that could have doomed mankind was kept safe in the underground. [music playing] Whoa!

Awesome! Damn, look at these things. What are they?

These are the Nike missiles. These are Nike Hercules missiles. They are lethal looking bastards, aren't they?

There are 12 individual missiles at this site, one of 12 sites that once ringed the Bay Area. At the height of the Cold War, there were 280 top secret Nike missile sites buried throughout the US. Whoa, are these armed?

No, everything here is inert. But this one here has been completely restored and looks exactly the way a Nike Hercules missile would look. They're huge.

So how fast is this thing going? This is traveling at about 2,000 miles an hour. This one gets up to 3.

65 times the speed of sound. No kidding, like a jet fighter, I mean, faster than-- Much faster than that, like a bullet. And this 6,500 pound white hot lawn dart comes back to Earth unguided.

Really? That's why they launch it at slight angles. And over the ocean.

Anywhere but here. This is the dangerous part up here, right? This is the warhead.

Where that red stripe is right up to the fins, that's your warhead. This is a W-31 nuclear device inside here. And this is 40 kilotons.

40 kilotons. Compare that to Hiroshima or something like that. Hiroshima was approximately 14 kilotons.

14. So this is three or four times more powerful than the A-bomb that we know. That's correct.

DON WILDMAN: Once a target had been identified by radar and confirmed by a spotter plane, the missiles could be raised to the surface, locked on target, and launched. Anyone within a quarter mile radius would be killed by sound waves alone. At 150 decibels, the force would literally push soft tissue into the bone.

Its flight path would cover 28 miles in 30 seconds, speeding straight up, then rotating 180 degrees, plummeting downward, and detonating in the center of the incoming bomber formation. So they're literally throwing a nuclear explosion up into the air. A very large nuclear explosion.

Wow. Minutes after the initial explosion, nuclear fallout far worse than Hiroshima would rain down on the city. Depending on weather patterns, up to 25% of the population could be dead of radiation poisoning within a few months.

By the 1970s, these deadly weapons were outdated, replaced on both sides by Intercontinental Ballistic Missiles that didn't rely on planes and pilots to guide them to their target. They could be launched from distances over 3,500 miles away. It cost millions of dollars to decommission the Nike missile sites nationwide.

This is the only one perfectly preserved in a state of readiness, a testament to how precarious the Cold War really was. It was potentially the most dangerous time in the history of this country. Really?

And we came that close on a number of occasions. Like when? Well, there's the Cuban Missile Crisis.

So take me to the Cuban Missile Crisis, October 1962. What would this place have been like at that moment? This place probably would have been on its highest state of readiness.

- Really? For how long? Well, that was defense condition one.

So the entire military was on a state of readiness. Is that DEFCON 1? Is that what that is?

- Yes. - OK. - Yeah.

So DEFCON 1, what's the difference than what we see here? Everybody was at their stations. And all the missiles were prepped and ready to go.

One button away from nuclear holocaust. Exactly. How many people die?

What happens to these places? Well, the Eastern seaboard I think had about 50 million people. Yeah.

You could look at that being destroyed. 50 million people just destroyed inside of a day. Yes.

Along with 50 million over there as well. And escalating. So the world could be destroyed in a single battle basically.

Had it flashed into a hot war, I think that's a very likely scenario. It feels especially present when you're standing with the very weapons that would be used. So in the nightmare scenario, these guys down here, the launch crew, have to pull this thing across.

This is the launcher rails. I can do this myself, which is remarkable considering-- considering this is 10,000 pounds of nuclear rocket. Comes right over here.

John, go ahead and set us off. [loud alarm] [music playing] Could we get this thing up all the way? Wow.

There she goes. Incredible. So this thing is armed and ready to go.

And when this takes off, it shoots 28 miles out there at the enemy target, Russian planes, Chinese planes coming towards our shores. And when that thing hits its target, blows those planes out of the air, watch out. World War III has just begun.

[music playing] Until the late 1840s, San Francisco was still a small settlement with an inhospitable landscape. But in 1848, gold was discovered in the Sierra Nevadas and tens of thousands of people flocked to the city. Unimaginable wealth was flowing out of that harbor every day in the form of pure gold.

Small settlement no more. San Francisco was now a boomtown. But in the coming years, the overcrowded streets and ramshackle neighborhoods would literally fuel a major disaster.

The city that grew from gold rush treasure is perched on top of the San Andreas fault line. State of the art subterranean engineering saved San Francisco once before and is the key to the city's future. When disaster struck in 1906, it was the brilliant design of this building, the San Francisco Mint, that preserved a fortune, rebuilt the city, and saved a nation from economic collapse.

Eric. Hey, Don. DON WILDMAN: Gold rush expert, Eric Christofferson, led us into a building that was the Fort Knox of its day.

Opened in 1874, the elegant 32,000 square foot main floor was quickly crowded with filthy prospectors right out of the mountains, looking to exchange gold dust and nuggets for cash. And so you're talking about people literally coming in from the streets with bags of gold, gold dust. And they start the process here.

First thing you would do is you would melt down the nuggets and dust and start turning it into the strips of gold or silver that could be then punched into coins. So the whole process takes place in this building? Yeah.

DON WILDMAN: $200 million of gold and silver were locked away in 11 impenetrable vaults. [music playing] So try opening the first two vault doors. God.

How heavy is this thing? It's about-- one of the vault doors weighs as much as 40 tons. Really?

Oh boy, ouch. Equally, equally heavy. - There you go.

- All right. Let's go in. DON WILDMAN: In the 19th century, we'd be shot on sight for entering this steel-lined vault without security clearance.

This had sacks upon sacks of burlap bags with silver coins in it. And it was stacked so thick that the weight of them has left the coins-- you can actually see all the coin imprints. DON WILDMAN: This building was made to protect these sacks of newly minted gold rush treasure from robbers and an even bigger threat, the ravages of mother nature.

They built this building to withstand earthquakes. So it was seismically equipped? Yeah.

DON WILDMAN: First, the clay beneath the building was replaced with layers of wet and dry sand. In case of an earthquake, the sand absorbs the jolts and protects the building, a technique so advanced it's still used by seismic engineers today. A four foot thick concrete slab reinforced with iron locomotive rails floated on top of this base.

It all supported a wrought iron frame covered in masonry and allowed the whole building to move as one impenetrable box. These hefty engineering precautions were put to the ultimate test on April 18, 1906. The earthquake hits.

And a fire ensues for three days. DON WILDMAN: That spring morning, a 7. 9 quake hit with a force of 15 million tons of TNT.

It toppled hundreds of buildings and ruptured the city's water system. When a cooking fire broke out, there was no water to fight it. The blaze spread, burning out of control for days and killing thousands.

The mint and its 58 workers and security guards who had taken refuge inside it survived the quake, only to have the fire close in. You've got flames rising, in some cases, as high as 20 stories. The temperature's 2,000 degrees.

Wow. It's encircling the whole mint. They close all those iron shutters.

The glass becomes liquid and just runs down. DON WILDMAN: The men would have been cooked alive and the building incinerated, except for a lucky stroke in the underground. In two different spots were artesian wells.

Mm-hmm. These wells were put into operation one week before the earthquake in 1906. Really?

Using water from their brand new wells, the mint's defenders put out the fires around the building, saving the vast fortune of gold and silver inside of it and staving off a national financial crisis. So this is one of two wells that were-- Exactly. --really the reason that this building survives the worst urban disaster in the country.

Today, San Francisco is once again banking on a massive underground engineering project to protect itself. But this time, something more precious than money is at stake, the city's drinking water. [music playing] Today, San Francisco has nearly completed construction on a massive reservoir underneath the sunset neighborhood.

It's part of a $65 million seismic upgrade of the city's water systems. It'll be capable of surviving even a devastating 7. 9 earthquake.

And we're the last TV crew allowed access before the millions of gallons of water come rushing in. Hey. Oh, hi, Don.

DON WILDMAN: I met with Paul Maza of the San Francisco Public Utilities Commission to see how the city is protecting its most valued resource from the next big one or a terrorist attack. So this is the Sunset Reservoir. Yes, it is.

So how big is this place? 20 acres. DON WILDMAN: The $4 billion project will safeguard the water for 2.

4 million people. The entrance is up in front of us here. But we're not going to allow you to show the entrance.

For security reasons, we like to keep a lot of this stuff off camera. Sure, the drinking water of San Francisco. The drinking water, we don't want to show access to the drinking water.

OK, turn the cameras off. [music playing] Whoa, it's cavernous. It's 10 acres.

It's four city blocks square. Really? 30 plus feet high.

No kidding. This will be filled with water? Filled with water.

So the 1906 earthquake, you're still worried about this earthquake that might hit. Yes, well, earthquakes don't just happen once. So we're anticipating up to a 7.

9 earthquake in the next 30 years. DON WILDMAN: In order to withstand the fierce shaking of a 7. 9 quake, the reservoir's 300 pillars are shored up by diagonal bracings and moment frames that hold up a roof over four city blocks long.

If an earthquake strikes, the moment frames allow the pillars to move up and down, but not side to side, while each of the 19 different roof sections can move independently. So this is the pipe that actually brings in the water. Yes, it is.

How big is this pipe? It's 54 inches in diameter. And that can bring in how much water?

40-50 million gallons a day. DON WILDMAN: For two years, this was a job site for 200 workers. But in just a few weeks, the only people coming down here will be scuba divers checking for cracks.

So this is the end point-- my echo. At the other end of this pipe is eventually the Sierra Nevadas. We are some of the last people to be standing in this huge water tank before tens of millions of gallons of water pour right through here and fill this place back up.

Isn't that right? Isn't that right? Yes, it is.

Yes, it is. [music playing] [music playing] Gold fever in California drew hundreds of thousands of Chinese immigrants from across the Pacific. A lucky few struck it rich.

But most were left to fend for themselves in the San Francisco slums, in a labyrinth of sin and vise hidden beneath the streets. By the end of the 1800s, Chinatown's underground was a snarl of coal tunnels, foot traffic passageways, and 2. 5 miles of brick sewer tunnels.

Above ground, crammed into tenements were hordes of men, workers fleeing famine and disaster in China. Racist immigration policies designed to keep the men from bringing over their families and settling in the US made it almost impossible for women to come here legally. So they were smuggled in as slaves.

Girls as young as five were forced to work as servants or as prostitutes. But a lucky few found freedom with the help of a crusader named Donaldina Cameron and a warren of coal tunnels that became the West Coast Underground Railroad. [music playing] I'm meeting a guy named Jack Shalpe.

He actually worked at Cameron House in the '60s and '70s, new Miss Cameron herself. He's going to tell me her amazing story. Hi, Jack.

Hello, Don. Nice to have you here. Thank you very much.

Welcome to Cameron House and Chinatown. DON WILDMAN: Jack has known women sold into slavery as little girls who escaped a lifetime of misery, because of this safe house, the tunnels beneath it, and the woman the girls called, beloved mother, but slave masters called white devil. So she was in the business of saving these young girls from this horrible fate.

That's right. Can we go in? Please.

DON WILDMAN: Today, Cameron House functions as a community center for San Francisco's Asian population. But 130 years ago, church aid workers would be sneaking around here in the dead of night, bringing in little girls and teenagers they had rescued from the brothels. But as Cameron House's reputation grew, hiding the girls got trickier.

So the owners would come looking for them here. So the owner would get his own policeman. Their policemen-- Ah, the corrupt.

--would help them get the girl with a search warrant. All right, so there was a little bit of corruption going on. Yeah, right.

DON WILDMAN: The owners used 30 year service contracts to legitimize their claims. When they showed up at the front door demanding the return of their property, the hunted girl was taken down the back stairs to a subterranean hideout. [music playing] So what's this?

This was a coal chute. And if the building was searched for one girl, the girl would hide in the tunnel. Can I look up there?

Oh, please. All right, well, this is a really small space meant for a very small person. But I think I can squeeze up here.

Wow-- this is tiny. So that's the street up above us, OK? So the cellar is over here.

Under the street is that way. This is essentially a coal tunnel. And if you were a small child, certainly, you could slip right back here.

So I'm going down there. All right, [inaudible]. Let's see how I get in this thing.

All right. These are tight spaces for, you know, meant for small people, little kids, not for me. At any given time, there might have been 10, 15 children in this place alone.

So if I was one of these little girls who'd been rescued, I'm put back here in this space inside the wall while the fate of my life is decided. And I would have been down here keeping perfectly quiet. The lawlessness and overcrowding in 19th century Chinatown was a recipe for disaster.

And in 1900, it boiled over in the form of a deadly epidemic. [music playing] At the turn of the century, the same years Miss Cameron was using the underground to save children from slavery, Chinatown was struck by the bubonic plague. The neighborhood was quarantined, locked down.

And the only way they could break the siege was by using the tunnels and sewers beneath the streets. The first bubonic plague victim appeared in 1900. Afraid of bad PR, the California State government went into cover up mode, sneaking the evidence, dead bodies, out of the quarantine zone.

Some of the sewer tunnels likely used for this covert operation are still in use today. City sanitation expert, Don Spears, is taking me down into the sewers. Can I take a look down there?

Yes. I'll get suited up, right? Yes.

Down under Chinatown. [music playing] Oof, this is a tiny, little sewer. Yes, it is.

How big is this thing? Five foot tall and three foot wide at the spring line. And these are typical sewers all around Chinatown.

Right. These sewers drain directly to the Bay. And the closest-- I can hear it draining.

As we're sitting in here, people are flushing their toilets and dumping their laundry. That's right. These well-engineered sewers carrying waste out of the city were also used as a superhighway, by wharf rats, many of them carrying a deadly disease.

Well, there's a nice little rat right there, good. So bubonic plague comes from fleas. Is that right?

Right, they were the transmitter. And the fleas are on the rats. Right.

The rats are in the sewers. Right. And they're migrating about.

When the rat dies and his body gets cold, the fleas jump off looking for another host. DON WILDMAN: The rats may have caused the plague. But it was people who kept it going.

Instead of treating the outbreak, they tried to deny it by quietly disposing of the corpses of plague victims. Hidden from view, conveniently leading to the harbor, the sewers became a macabre garbage chute. So if you had to get a body out of here, out of Chinatown, you get them through-- you take it out through the tunnels.

This would be the easiest way. DON WILDMAN: Tightly wrapped corpses would be lowered down through a manhole and strapped to a board. The board rested on the rat rails on either side of the narrow tunnel.

Since the tunnels ran downhill, it was easy work to push the dead weight 800 yards to the end of the line, San Francisco Harbor. And the bodies were never seen again. Do they have any idea how many people died in this plague?

Well, they do of the bodies that they actually found. Right. And there was I think over 100 or so.

But there's no way of counting the ones they didn't find. DON WILDMAN: Isolation and racism caused human suffering to fester here in Chinatown. And for both the living and the dead, one way out was the underground.

[music playing] [music playing] The same counterculture revolution that produced San Francisco's fabled summer of love spawned a lesser known, more subversive movement called the Suicide Club. It's a secret group of urban explorers whose creed it is to live every day as if it's their last, to confront their fears, and to enter into a world of chaos. And no sooner did they enter into San Francisco's abandoned and forgotten underground then they discovered that their upstanding city was also a top secret military stronghold buried beneath the Earth.

[music playing] I'm meeting a guy named John Law, one of the original members of the Suicide Club. He's taking me to some of the most secret undergrounds in the city. In fact, I'm not even allowed to know where they are.

Hi. - Hi. - Hey, good morning.

- I'm Don. I'm John Law. Pleased to meet you.

DON WILDMAN: For almost a decade, John and his fellow rebels got a thrill out of defying authority and pushing buttons. They rode trolley cars naked, climbed bridges, and explored the vast underworld of an abandoned military complex that few in the City of Love knew about. Official entrances to the World War II and Cold War bunkers were sealed up in the 1970s.

Nice to meet you. I'm Don. But John and a band of urban explorers refused to let a huge chapter of the city's history just rot away in the dark.

So they found a way in. We're not going to tell you what the location is. You're going to be blindfolded.

But we're going into an underground chamber that is not accessible to anyone. DON WILDMAN: To protect the location of the hidden access point, our crew had to be blindfolded while we rode there. And that meant we had to turn over our cameras to strangers.

Take us to the underground. All right, let's roll. DON WILDMAN: We had no idea where we were going, except that it was somewhere underneath Golden Gate Recreational Area, which covers almost 75,000 acres.

Rumor has it that below this park lies a top secret underground military complex first developed during World War II. Make sure those boys can't see anything back there. Keep those on, guys.

We're walking you up so-- I'm all connected to this camera. I understand. Come on up here.

We're almost there. And another big step up right-- got it? Feel right here.

There's like a piece of-- yeah. Flat on your butt, OK. All right, wow, God, could it be a little tighter?

[music playing] [inaudible] Thank you. You all good? Yeah, good.

We just came down about 30 feet from here. Outside is there. I have no idea where that is, where we are right now.

But the drop is down another-- 50 feet. --50 feet down. What is this shaft we just came down?

It's a long concrete shaft. It's an air shaft and also access to probably a viewing post up above. Survival supplies furnished by Office of Civil Defense.

How cool is this? Total artifact, Cold War definitely. Yeah, and it's big.

Oh, look at that. DON WILDMAN: John estimates this bunker covers as much as 82,000 square feet underground. We're seeing the racks for carrying ordnance.

This would have been a major military base basically. Yeah, this is part of a major military complex that went on for miles, and miles, and miles. To the best of your knowledge, what did this place look like in its original state?

Well, it would've looked pretty much exactly like it does now, but without all of the bad '70s graffiti. So concrete corridors, they had an overhead rail here, which is rusted away. They had bunks set up in here, their kitchen.

They would've had living quarters. They would have had storage for their weapons. Dating back to around the '50s maybe?

I can't say the period. I don't want to tip you off too much. But let's say sometime between 1940 and 1955.

OK. DON WILDMAN: John wouldn't say. But this cavernous underground space has all the hallmarks of a World War II munitions bunker.

The war in the Pacific depended heavily on ships, cargo, and munitions from San Francisco Harbor. So existing fortifications dating back to the Civil War were reinforced. And new larger bunkers were dug deep beneath city park land.

So this rack above my head would have been used to move artillery ordnance, I guess. So you got trucks moving through here. You got soldiers moving in and out.

Maybe there's a gun emplacement above my head. I don't know. I don't know where I am.

But if all this was as serious as it looks, there was a lot of activity down here. So when you first started going underground back in the '70s, were you surprised at how much military infrastructure was in San Francisco? We were a little bit surprised.

And then after we were exploring for some time and we went into a variety of different bunkers of different ages. I mean, tunnels that were as old as the 1860s. And it has always been viewed as a major target, this part of the country.

San Francisco certainly has. I mean, you know, somebody's got to get those hippies. [inaudible] What is that?

That's in the air shaft that goes up to the [inaudible] post. - Can I take a look? - Yeah.

Need a lift? Yeah. It's weird to think that this place is all completely sealed off.

This country went through 20, 30 years convinced that they were going to get attacked. And so they were building fortifications like this deep underground. In its day, this may have been a top secret location, defended by fences and military patrols.

Now its only protection is the fact that almost no one knows it's even here, except for the Suicide Club. I can hear people. So this is park land that's over us?

Yes. [inaudible] Within a lot of the various park land. That's true.

The public is out there. Yes. Everybody thinks these places are [inaudible].

. You can look through there. There they are.

So we're trying to stay perfectly quiet. Because we don't want anybody outside to know that you can actually get in here. This would be a bad thing if everybody knew how to get in here.

It's dangerous in here. The Suicide Club's subterranean exploits are a lot like our crew's. We're all digging down to uncover the stories hiding just out of sight in the underworld.

Ever since we first started coming down here, since they sealed the bunker, we always leave a little note. To the Suicide Club, thanks for taking us down. Cities of the Underworld.

All right. In San Francisco, boom times have gone hand in hand with brutality and catastrophe, earthquakes, fires, and plague. But few know how close the city has come to enemy attack.

The only thing that saved it, the massive fortifications of its underworld.