Visible below the waves are memorials to the city's Gold Rush dead.

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

Tiki luxury on Nob Hill.

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

San Francisco's newly reopened hands-on science museum.

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

A pair of slides and a tree-lined stair corridor have been an urban oasis for nearly 40 years.

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

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

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

Its buzzing collection honors vibrator history.

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

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

There is no trying to fall in love with this Star Wars fountain, you just do or do not.

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

This shop specializes in oddities and Victorian-inspired wonders.

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

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

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

The old Niles Canyon Aqueduct in the San Francisco Bay Area is a bemusing and secret trail through nature for wayward travelers.

From the sky, a kaleidoscope of color brightens the grey landscape of the San Francisco Bay.

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

A trail weaves through the verses of a poem illustrated by stone sculptures inspired by Native American pictographs.

Four miles of pipelines form the model of still-functioning retro-tech efficiency.