Muir Woods National Monument is a unit of the National Park Service on Mount Tamalpais near the Pacific coast, in southwestern Marin County, California. It is part of the Golden Gate National Recreation Area, and is 12 miles north of San Francisco. It protects 554 acres, of which 240 acres are old growth coast redwood (Sequoia sempervirens) forests, one of a few such stands remaining in the San Francisco Bay Area.