The Parks Conservancy in partnership with the National Park Service engaged 34,484 volunteers who put in 513,884 hours in 2011 alone. That kind of work would cost $10.9 million on the open market.

Most of the more than one million tourists who visit the famous former prison annually never get to experience Alcatraz...

Andy Goldsworthy plots the curves of new Presidio creation

A newly built trail and boardwalk on the southern edge of the Presidio is as much a window into San Francisco's maritime history as it is a path through restored sand dunes and coastal habitat.

May 2011 marks the 10th anniversary of the $34 million restoration of Crissy Field, a 1.3-mile stretch of shoreline between the new Crissy Field Center on the east and the Warming Hut on the west - one of the great vistas anywhere.