Battery Townsley, at Fort Cronkhite, was San Francisco's most extensive—and most secret—World War II military fortification.
From 1940 to 1948, it mounted two massive battleship guns and housed more than 100 soldiers in an extensive network of underground tunnels; during the Cold War, it was used as an underground research facility.
Long closed to public access, Battery Townsley is now open and the public is invited to visit and explore this labyrinthine fortification!
Battery Townsley is reached via a moderately strenuous hike up the Coastal Trail, approximately one-half-mile north of the Rodeo Beach parking lot. Open the second Sunday of each Month. 12 PM - 4 PM
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