The Golden Gate National Park is home to the Presidio Army Museum. The Presidio served as a key military command center during the Mexican War, the Civil War, the Spanish-American War, World War I, World War II and the Korean War. The site housed an old military hospital dating back to 1857. There are displays of relics and documents which show the part played by the military in the growth of San Francisco. The post was first occupied by the Spanish in 1776. The United States moved into the post in 1846 when Marines from the USS Portsmouth landed and raised the American Flag. In October, 1994 the Sixth U.S. Army vacated the Presidio and it ceased being a strategic military hub. Visitors to the museum can experience the history of the Main Post in a number of ways. An audio walking tour reveals the history and development of the Presidio. The audio tour can be experienced using a cell phone or MP3 player as guests stop at the 18 individual destinations on the Main Post grounds. Many tourists prefer driving around the grounds and stopping at the various points of interest. The former post is located in view of the Golden Gate Bridge on more than 1100 acres. The sights from the Presidio offer visitors beautiful panoramic views of the grounds and San Francisco Bay. The visitor's center furnishes guests with interesting historical facts about the post.