Muir Woods National Monument is a United States National Monument located in Marin County, California. It was established in 1908 to protect the old-growth redwood forest of coast redwoods, which are among the tallest and oldest trees in the world. The monument is named after naturalist John Muir, who was an early advocate for the preservation of wilderness in the United States. The monument is managed by the National Park Service and is open to the public for recreational activities such as hiking, camping, and picnicking.