San Vicente Mountain Park
Time Out says
During the Cold War, San Vicente Mountain was one of 16 Nike missile launch sites in LA. Today, its decommissioned radar tower provides one of the best 360-degree views in the entire county. On clear days you can see Palos Verdes, Downtown and the entire Valley, including the adjacent Encino Reservoir. You'll find bathrooms, picnic tables and hiking trails into the "Big Wild" wilderness area scattered elsewhere around the park. Just be aware that getting there involves a windy, gravelly drive up an unpaved section of Mulholland Drive.