The San Francisco Recreation and Park Department (415/831-2700. www.parks.sfgov.org) maintains 132 public tennis courts throughout the city. All courts listed here are free except for those in Golden Gate Park. Golden Gate Park (John F. Kennedy Dr., near 3rd Ave. 415/753-7131 reservations; 415/753-7001 information) has 21 tennis courts. Court fees are $5 to $10. Call for weekend reservations. Weekdays are first-come, first-served; avoid times after 4 PM on weekdays, when school teams show up for practice. In the southeast corner of the beautiful Presidio, Julius Kahn Park (W. Pacific Ave. between Spruce and Locust Sts., Presidio) has four courts; the park and fantastic playground are great distractions for kids if the courts are full when you arrive. Mission Dolores Park (18th and Dolores Sts., Castro) has six lighted courts, available on a first-come, first-served basis. Mountain Lake Park (Lake St. and 8th Ave., Richmond), on the southern edge of the Presidio, has nice courts; it's an in-the-know tennis spot.