A psychedelic labyrinth on the San Francisco bay.

A huge musical instrument played by the ocean.

The remains of a ruined mansion memorialize the 1906 earthquake.

Floating man-made island and upscale restaurant.

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

An elaborate gift from Claus Spreckels is now a piece of San Francisco history.

Forgotten and then destroyed by fire, this was once one of the largest saltwater swimming pools in the world.

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

A hidden subterranean installation offers a view of the sky.

A masterpiece in Golden Gate Park by virtue of the artist’s debt.

This giant head is all that remains of a once proud statue that survived an earthquake but not a fall off of a wagon.

An invitation-only museum of items natural and bizarre, arcane and exotic.

San Francisco's first World's Fair, dedicated to the wonders of California.

The restored and active Victorian-era final resting place of San Francisco.

The stones that traveled from Spain to eventually become a holy place for San Francisco's nature worshippers.

This 19th-century church is now a popular roller rink.

This turn of the century masterpiece has a mysterious goaty interloper.

An overlooked and unassuming engineering marvel.

These subterranean storage areas hold emergency water reserves.

This one-block alleyway is stuffed with street art that is colorful, cultural, and intensely political.

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

A shop full of natural curiosities, carnivorous plants, and costumed taxidermied mice.

A library built during San Francisco's pioneer times is a student's retreat, bibliophile's sanctuary, and chess player's delight.

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