The Presidio of San Francisco (originally, El Presidio Real de San Francisco or Royal Presidio of San Francisco) is a park on the northern tip of the San Francisco Peninsula in San Francisco, California, within the Golden Gate National Recreation Area. It has been a fortified location since September 17th, 1776 when New Spain made it the military center of their colonization of the area. It passed to Mexico, which in turn passed it to the United States in 1848. Photo by Carol Highsmith.