The randomness of this wall of lava lamps helps encrypt up to 10 percent of the internet.

The remains of a ruined mansion memorialize the 1906 earthquake.

A nondescript building that's been functioning as a speakeasy for nearly a century and a half.

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

Tiki luxury on Nob Hill.

A collection of 20th-century automata, penny arcade games, and musical contraptions.

A museum befitting the city responsible for supplying the majority of the world's LSD.

Get lost in this haunting fairytale art walk through a man-made eucalyptus grove.

Its buzzing collection honors vibrator history.

An artsy hidden staircase leads to breathtaking views of San Francisco.

A psychedelic labyrinth on the San Francisco bay.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

Adolph Sutro's little-known, geographically inaccurate, deprecated monument.

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

The final resting place of the Emperor of the United States and Protector of Mexico.

The garage at the childhood home of Steve Jobs was a hangout for the founders of Apple, even if they never built computers there.

Location of the most powerful laser in the world, and the potential birthplace of tiny stars.

The longest burning light bulb in the world.

Neither Spanish settlers nor anyone since has been able to tell who built these strange California rock walls.

The first high-tech company in the valley that actually worked with silicon devices.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.