The Empire Mine is "one of the oldest, largest, deepest, longest and richest gold mines in California."

Barely visible foundations remain where Stow Lake’s “observatory” once welcomed visitors.

Join the circus for a few lessons to learn clowning, acrobatics, and Chinese contortion.

America's original house of worship for Spiritualism, the religious movement based on communing with the dead.

After four years of grasshopper plagues, this chapel was erected as a plea to God to make them end.

San Francisco's oldest operating hotel, with a Victorian atmosphere and a "haunted" fourth floor.

San Francisco's most expensive hotel suite includes a secret passageway rumored to have been used by JFK.

The remains of a 12th-century chapter house in Golden Gate Park.

San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

A psychedelic labyrinth on the San Francisco bay.

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

A huge musical instrument played by the ocean.

Half of a house.

San Francisco's urban bison herd has persisted in the face of extinction, development, and disease.

This private residence was the template for one of the most beloved television homes of all time.

This concrete tangle of square pipes has stood as a proud thorn in the city's side since the '70s.

A historic hotel that made a cameo in Hitchcock's classic film has no intention of letting guests forget its fame.

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

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

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

A ruined hotel with an unlucky history and an eerie present.

Nuclear waste dump site now an environmental sanctuary.