Spiral labyrinth hidden in the hills above Oakland, CA.

The stone walls of a home built to withstand a California wildfire still stand after more than a century.

Secret Manor, a house full of legends, the least of which is the haunting of long-deceased ladies of pleasure.

Another of California's unused Cold War missile defense complexes has become a graffiti gallery.

Elephant seals and sea lions have turned the abandoned buildings on this island into their endangered love shack.

Built by the inventor of the radio, this abandoned hotel has housed early radio employees, military men, and a dangerous cult.

The "Fun Spot of the Desert" is now a haunting ruin, and a reminder that putting a water park in a desert is a bad idea.

Hidden beneath a lake for decades, this brutalist mine has now emerged from beneath the receding waters.

The graffiti-covered remnants of a former triangulation station are balanced precariously on this California peak.

Costumed elves and mountain bikers co-exist peacefully at this abandoned Christmas-themed adventure park.

This old mining town, deep in the California desert, has a year-round population of one.

An ominous concrete cube cuts a dystopian silhouette atop this California mountain.

Once a place of peaceful repose, this sanitarium now faces an uncertain future.

Once America’s most beautiful army base, this abandoned military fort on the coast of Monterey Bay has been left to the elements.

A long-vacant Scottish Rite temple in Hollywood has been converted into an art museum filled with Masonic relics.

An abandoned boat that's been stranded mysteriously for decades.

This little gem of Spanish Colonial architecture has been abandoned since the 1950s.

The now-abandoned tunnels were built for the transcontinental railroad on the route where the first wagon train entered California.

The overgrown ruins of a once thriving World War I-era copper mine.

The abandoned train depot now doubles as a well-placed rest stop for those who take the road less traveled.

An abandoned Cold War missile radar site.

An abandoned car and strange wooden debris are among the scattered remains of the old sand and gravel quarry.

The remains of a deserted steamboat sit rusting beside an old ferry pier and an abandoned train platform.

A lawless town deep in Death Valley was famous for its riches and death rate.