* * * * * Flag of New Spain 1776 . The Presidio of San Francisco (originally, El Presidio Real de San Francisco or The Royal Fortress of Saint Francis) is a park and former U.S. Army military fort on the northern tip of the San Francisco Peninsula . F rom 17th September 1776, it had been a fortified location, when New Spain established the presidio to gain a foothold in Alta California and the San Francisco Bay . Then it passed to Mexico, and in turn passed to the United States in 1848. On 1 st October 1994, it was transferred to the National Park Service , ending 219 years of military use and beginning its next phase of mixed commercial and public use. ...