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

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

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

Its buzzing collection honors vibrator history.

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

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

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

An overlooked and unassuming engineering marvel.

A miniature view of the park, caught in time.

A hidden subterranean installation offers a view of the sky.

A psychedelic labyrinth on the San Francisco bay.

The artist David Nash planted a circle of trees in 1977.

This secret garden has bloomed into London's most unique hub of urban creativity.

Art in the form of a winding, man made crack in stone.

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 garden oasis filled with flowers mentioned in the works of William Shakespeare.

Thirteen trees representing the original thirteen colonies were planted with soil from historic Revolutionary battlefields.

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

This museum inside a museum tells the story of London's timepieces.