In San Vicente Mountain Park, you can drive pretty close and then take a quick hike up to this Nike Missile Site, named for the missile project, not the shoe.  

During the Cold War in the late ’50s, Army specialists monitored the skies from this high point between Los Angeles and the Valley, looking for Soviet air strikes. The technology at the site could both detect enemy aircraft and assist anti-aircraft missiles launched from a nearby facility.

Years of disuse later, the missile site is now part of a public park. People can stomp up the steel structures and enjoy the sweeping views in all directions. Not much has changed, or what’s been added is deliberately made to match the existing structures, so it still sort of feels like somewhere you’re not allowed to be.