An abandoned cyanide mill is now a haunting magnet for graffiti and illegal parties.

The old Niles Canyon Aqueduct in the San Francisco Bay Area is a bemusing and secret trail through nature for wayward travelers.

An abandoned, unfinished mansion on grounds strewn with lava rocks.

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

San Francisco Bay's ghost town.