It was to be part of a fortification in Marin that could launch shells that weighed as much as a Volkswagen more than 30 miles, and stood in defense of the Golden Gate and San Francisco Bay harbors.
But the battery's guns were never activated, and after the Cold War ended the bunker was abandoned. As the military left, the public moved in and began to explore the subterranean site — some 500 feet long and containing about a half-dozen chambers. When the Golden Gate National Recreation Area took over the property in the early 1970s it eventually closed off the main entrances to keep people out.
But people have been sneaking in ever since, and the Park Service decided someone could get hurt. So last week, volunteers were invited to photograph the enclosure before it was sealed off. Reporter Kate Szrom files this video for us: