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

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

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

This little blue house pokes out over the campus of UC San Diego, seven stories high.

Dive bar built out of the remains of a whaling ship.

A deserted hodgepodge of experimental structures designed by nearby university students.

The "3rd largest" city in California is an empty mirage of suburbia in the middle of nowhere.

A fashion designer's dazzling world of Japanese collectibles is hidden in a warehouse downtown.

A library and museum dedicated to typography.

The fossilized remains of ancient California redwoods.

Hidden above a drug store on a nondescript corner of Lincoln Heights is a private clubhouse for intrepid explorers.

This traditional garden in the San Fernando Valley doubled for Star Fleet Academy, and is irrigated entirely by wastewater.