Beale Air Force Base, California

Beale AFB is a high-altitude reconnaissance aircraft base. Located in the Sacramento Valley, it is home to the 9th Reconnaissance Wing (one of the few stateside reconnaissance wings), which once flew the SR-71 Blackbird until its retirement in the mid-1990's, and still flies the nation's fleet of U2 spy planes, as well as the RQ-4 Global Hawk - a high-altitude, long-endurance drone (UAV). Beale is also one of five U.S. locations for the Phased Array Warning System, a unique radar system housed in a large pyramidal building. Also called PAVE-PAWS, the system tracks land, air, sea, and space-launched objects over the Pacific Ocean (there is a similar PAVE-PAWS on Cape Cod that looks out over the Atlantic). The base covers 23,000 acres.