Inside a 'haunted' 150-year-old million-dollar castle hidden away in San Francisco with underground caves and a toilet in the shape of a throne

Good luck trying to spot San Francisco’s Albion Castle at 881 Innes Ave. from the street — the property is shielded by high fences and towering trees.

It sits in Bayview, one of San Francisco’s southernmost neighborhoods that fronts the bay.

Read more: San Francisco's housing crisis is so out of control that one of the city's last districts seized by big tech boasts 'cheap' homes priced at $800,000 — here's what the neighborhood is like

The castle is nestled on an unassuming street in the neighborhood.

More modern homes — not of the medieval-looking variety — surround Albion on either side.

A pair of gates and stone pillars stand at the entrance. It's difficult to even catch a glimpse of the castle from anywhere outside.

But once the gate opens …

… the 150-year-old castle comes into view.

The current owners, the Gilbert family, bought the castle in 2012 for $900,000, Jennifer Gilbert told Business Insider.

Jennifer's dad, Bill Gilbert, is a retired San Francisco police officer and real-estate investor who grew up in Bayview and has admired the castle since he was a kid.

It hasn’t been lived in since the Gilberts bought it, but it was originally built as a personal residence — at least partly.

Source: Atlas Obscura

The castle was built into a hillside in 1870 by John Hamlin Burnell, an English immigrant who planned on using the castle to run a brewery that could supply the 800-plus saloons that dotted the city at the time.

Source: Atlas Obscura

He intentionally chose to construct the castle where he did — the castle sits atop an underground natural aquifer fed from the Hetch Hetchy Valley that supplied him with water to use for brewing the ale.

Source: Atlas Obscura

Burnell carved out two 200-foot cisterns to capture 10,000 gallons of natural, cold spring water a day.

Source: Atlas Obscura

Two of the cisterns are in a cave deep beneath the castle. They’re accessible by a narrow and low-hanging passageway.

The water is clean and potable today, and 10,000 gallons of it are still produced daily. The water feeds into the bay.

A third cistern is housed in a cave right above the other two. A plaque reading "handhewn caverns" is displayed in the stonefront of the cistern.

The castle served not only as the warehouse and production site for the ale but also as Burnell's home. He modeled the castle after Norman-style castles and named his business the Albion Ale & Porter Brewery.

Source: Atlas Obscura

At the time of the castle’s construction, Bayview and Hunter’s Point housed a Naval ship-building yard.

Source: Atlas Obscura

So Burnell used the easily accessible ship ballast and wood to build the castle.

Source: Atlas Obscura

The original ceiling beams, constructed of ship wood, are still in parts of the castle like the dining room.

The courtyard at the front of the castle was where the Albion ale was produced.

A pair of long-forgotten ovens, once used to process barley, still rest in the corner.

The Albion Brewery was kept up and running until 1919, when Prohibition closed it down. The castle started a new life as the Albion Water Company, producing bottled drinking water until 1947.

Source: Atlas Obscura

A sculptor named Adrien Voisin bought the castle in 1938 and added decor befitting a medieval fortress.

Source: Atlas Obscura

He integrated intricate woodwork into the home. The touches he made to the property are largely what remains today.

Source: Atlas Obscura

Stepping into the residence part of the castle is a bit like stepping into a fairy tale.

The structure is four stories tall and is narrow, with either sitting rooms or bedrooms occupying each floor.

The entrance opens up to a spacious living room decked out in rich colors.

What looks like a medieval chandelier hangs from the ceiling. Gilbert said it came with the property.

Off the living room is the kitchen, which was updated about 10 years ago, Gilbert said. Modern appliances were installed.

Stained-glass panels on the cabinetry were added during the time that Voisin owned the place.

Through the kitchen is a dining room.

In the living room is a staircase leading to the upper stories. The second story opens into a sitting room.

And through a hallway is perhaps one of the most eccentric additions to the house. What’s a castle without a throne anyway?

The throne room, one of the castle's three bathrooms, was added during the Voisin era. The artist had the toilet built into a throne, complete with a headboard and armrests.

An ashtray sits in one of the armrests.

Gilbert said that the throne room may have been the selling point for her dad.

The only private bedroom is located right off of the throne bathroom.

Up another flight of stairs is an open bedroom.

A second full bathroom is on this story. A third is located in the courtyard.

And all the way up at the top of the tower is a sitting area.

In 1961, a highway construction plan threatened to demolish the then-nearly-century-old castle. Its status as one of the only natural water sources that can’t be contaminated saved it from destruction.

Source: Atlas Obscura

The case was made that in the event of a nuclear attack on the city, the castle's underground aquifer could provide water to the city and its inhabitants.

Source: Atlas Obscura

That’s still the case today — Gilbert said that the castle’s owners since then have had to give written permission for the city to come in if there was ever a nuclear disaster.

It became a historically protected landmark in 1973.

Source: SF Curbed

Jennifer Gilbert said that during the tech boom of the 1990s, the castle started attracting Silicon Valley tech workers.

The tech support center for the blog Laughing Squid was housed in Albion Castle for a year, Gilbert said.

Source: 7X7

Gilbert said the techies had inner tubes in the underground caverns at one point. "They had fun here," she said.

The castle passed to a new owner in 1998. Online city guide CitySearch cofounder Eric Higgs used the property as a personal residence and art studio.

Source: Atlas Obscura

It was eventually sold at auction for $2.1 million in 2005 before Napa County brewers sought it out to re-launch the Albion Brewery company, but it never panned out.

Source: Atlas Obscura

Since it was purchased by the Gilbert’s in 2012, the castle has been used for events on the smaller side, and the family is selective with who they allow to book the older property.

"We don’t want a lot of people trampling all over the place," Gilbert said.

There has been a Halloween party hosted at the castle, a Christmas party for the local hat shop Goorin, and a visit from the reality TV show "Real Housewives of New Jersey."

Software giant Adobe took to the castle during a security breach a few years back, Gilbert said. A team of about 20 people worked off-site at the castle for two days while security issues were worked out.

Gilbert said Google has held a dinner party at the castle as well.

There haven’t been any weddings yet, but Gilbert said they’ve had a lot of inquiries for them. She said that could be a possibility in the future, but they’re still fine-tuning the castle to make it fit for a wedding.

There are also plans to re-launch a water-bottling company to make use of the 10,000 gallons of water produced daily in the underground caves.

As for the question of hauntings in the castle, Gilbert said that she has never seen anything herself personally, but there have been sightings by people on the property.

There have been reports of Native American spirit sightings. Long before the castle was constructed, the natural spring was a pond frequented by local Native American peoples.

Source: KALW

And Gilbert said that a girl with long dark hair has been seen looking out of the window in the tower.

Gilbert said the paranormal show "Ghost Adventures" filmed at the property recently, and an episode featuring the castle is slated to air on the show's upcoming season.

Paranormal reports aside, Gilbert said she feels perfectly safe in the castle.

Though her dad doesn’t live at the castle, she said he’ll come and have coffee and sit outside to enjoy the property.

She also said he's gotten offers for the place in the last couple of years for far more than the $900,000 he paid for it. But he's wanted the castle for decades, so, for now, it'll stay where it is: in the family.