Well off the beaten track for tourists, but only 8 miles from downtown San Diego, this is one of the nation's largest urban parks. Encompassing some 5,800 acres, it includes abundant bird life, two lakes, a picturesque stretch of the San Diego River, the Old Mission Dam (probably the first irrigation project in the West), and 1,592-foot Cowles Mountain, the summit of which reveals outstanding views over much of the county. The park boasts more than 40 miles of trails, including a 1.5-mile interpretive trail; some paths are designated for mountain bike use. There's also a 46-space campground (tel. 619/668-2748). Mission Trails was founded in 1974, when the area surrounding Cowles Mountain began to experience a housing boom, leading city and county representatives -- working with community planners -- to make an initial purchase of land. In 1989 the first park ranger was hired; in 1995 the slick visitor center opened.