The Santa Monica Mountains National Recreation Area (SMMNRA) is a national recreation area containing many individual parks and open space preserves, located primarily in Southern California's Santa Monica Mountains. Located in greater Los Angeles, two thirds of SMMNRA's parklands are in northwest Los Angeles County and the remaining third, including a Simi Hills extension, is in southeastern Ventura County. It is administered by the National Park Service in coordination with state, county, municipal, and university agencies.
In size, the Santa Monica Mountains National Recreation Area is the largest urban national park in the world. It is also one of the best examples of a Mediterranean climate ecosystem and it protects one of the highest densities of archaeological resources in any mountain range in the world.