The Golden Gate National Recreation Area is one of the largest urban national parks in the world. It was established in 1972 as part of a trend to make national park resources more accessible to urban populations and bring “parks to the people.” Golden Gate National Recreation Area’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. These lands represent one of the nation’s largest coastal preserves and attract 16 million visitors each year, making Golden Gate National Recreation Area one of the National Park Service's most frequently visited units. The park contains numerous historical and cultural resources, including Alcatraz, Marin Headlands, the Nike Missile Site, Fort Mason, as well as Muir Woods National Monument, Fort Point National Historic Site, and the Presidio of San Francisco. Those points of interest contain a variety of archeological sites, military forts and other historic structures, which present a rich chronicle of two centuries of history. Golden Gate National Recreation Area is also rich in natural resources — it comprises 19 separate ecosystems in seven 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. Labeled a "national recreation area," the lands of the park offer scenic vistas, nationally significant cultural resources, and belts of vegetation scattered across the urban landscape. Balancing the competing needs of these lands and their many constituencies is the dominant feature of park management. Few urban shorelines contain the kind of diversity of Golden Gate National Recreation Area. The park wraps around San Francisco's northern and western edge, offering a series of scenic, historic, urban, and natural features. The entrance to the city's harbor at the Golden Gate is one of the world's most famous views. Golden Gate National Recreation Area’s city shoreline provides a historic as well as scenic perspective of San Francisco: Ships that fostered early immigration and trade, and fortifications built to defend residents, are all within the park.