Muir Woods National Monument is a unit of the National Park Service on the Pacific coast of southwestern Marin County, California, 12 miles (19 km) north of San Francisco and part of the Golden Gate National Recreation Area. It protects 554 acres (224 ha),[4] of which 240 acres (97 ha) are old growth Coast Redwood (Sequoia sempervirens) forests, one of a few such stands remaining in the San Francisco Bay Area. Photo by Carol Highsmith.