The Golden Gate National Recreation Area (GGNRA) is one of the largest urban national parks in the world. GGNRA’s 75,398 acres of land and water extend north of the Golden Gate Bridge to Tomales Bay in Marin County and south to San Mateo County, encompassing 59 miles of bay and ocean shoreline. The park contains numerous historical and cultural resources, including Alcatraz, Marin Headlands, Nike Missile Site, Fort Mason, as well as Muir Woods National Monument, Fort Point National Historic Site, and the Presidio of San Francisco. These sites contain a variety of archeological sites, military forts and other historic structures which present a rich chronicle of two hundred years of history, including Native American culture, the Spanish Empire frontier, the Mexican Republic, evolution of American coastal fortifications, maritime history, 18th century and early 20th century agriculture, military history, California Gold Rush, Buffalo Soldiers, and the growth of urban San Francisco. Golden Gate National Recreation Area is also rich in natural resources—it is comprised of 19 separate ecosystems in 7 distinct watersheds and is home to 1,273 plant and animal species. With 80 sensitive, rare, threatened, or endangered species —including the Northern Spotted Owl, California Red-legged Frog, and Coho Salmon— the park has the fourth largest number (33) of federally protected or endangered species of all units in the National Park System.