A popular tourist cave with a dark past.

A still functioning vaudeville carousel that has operated for over a century boasts a colorful menagerie and past.

Rodin's famous depiction of Dante's 'Inferno', amidst a sculpture garden of many of his other works.

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

The remains of a ruined mansion memorialize the 1906 earthquake.

A 300-ship graveyard, with a few still visible at low tide.

The largest permanent Monopoly board makes one of the longest games even bigger.

The one-time watch house for incoming ships at the Golden Gate now stands abandoned and hidden in trees.

Staircase winds down the side of Telegraph Hill through gardens, wild parrots flying overhead.

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

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

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

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

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

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

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

A sudden forest of traditional Papua New Guinean art works is hidden in a corner of Stanford University.

10,000 flowered plants bloom in the City of Roses.

Beyond being incredibly fun, not much can be said about the Hole with certitude.

City Council meetings still happen in this historic building, impeccably preserved on the inside.

Featuring a casually threatening atmosphere along with dessert and coffee to die for.

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

One of the largest free-standing structures ever built, this dirigible hangar is now simply a giant skeleton.

The graffiti-covered remnants of a former triangulation station are balanced precariously on this California peak.