A 300-ship graveyard, with a few still visible at low tide.

Big gun installations, built over a massive cemetery, now abandoned & hidden in trees.

In this century-old literary safehouse, print is alive and well.

The one-time watch house for incoming ships at the Golden Gate now stands abandoned and hidden in trees.

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

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

A favorite haunt of dinosaur loving children and hallucinogen loving hippies alike.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

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

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

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

Its buzzing collection honors vibrator history.

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

A winding path built in secret on the edge of the continent.

The only theatre in the world constructed specifically for sound movement.

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

A 140-year-old castle with underground caves hidden in San Francisco.

A psychedelic labyrinth on the San Francisco bay.

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

A huge musical instrument played by the ocean.

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

A gothic palace of endless stalagmites and pseudoscorpions waits within one of the world's most beautiful caves.

This famous Nevada gold mine, once a hotbed of Wild West shenanigans, is now open for tours.

A mining town once rife with murderous disputes over its copious treasures now creates income as a popular spot for photo shoots.