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

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.

The second building of its name to occupy this location might be the finest flatiron building in San Francisco.

Only hotel where you can legally launder money.

These subterranean storage areas hold emergency water reserves.

Created in 1972, the famous sculptor's intricately detailed monument to San Francisco is overflowing with city landmarks.

An art supply shop holds the secrets of this quiet neighborhood's raucous Barbary Coast past.

A shining, cold, black organ lies in San Francisco's financial district.

A monumental cross hides in the trees in Golden Gate Park.

A man-made island in scenic San Francisco Bay.

Inside an old airplane hangar, friends and strangers alike play on a massive trampoline.

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

San Francisco's oldest surviving monument and meeting place for 1906 survivors.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

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

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

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.