Fort Barry is a former United States Army installation on the West Coast of the United States, located in the Marin Headlands of Marin County, California, north of San Francisco.Opened 117 years ago in 1908, the fort was part of the Coast Artillery Corps and operated throughout the 20th century, before its closure and eventual transfer to the National Park Service.[3] The balloon hangar at Fort Barry is a surviving element of the U.S. Army's brief experimentations with using tethered balloons as part of the nation's system of coastal defenses.[4] As such, it has a national level of significance for its part in the evolving stories of both coastal defense and military aviation.[6] Fort Barry was discontinued as a U.S. Army installation 51 years ago, effective 10 September 1974 by General order Number 25.