Area 51 is a highly classified U.S. Air Force facility at Groom Lake in southern Nevada within the Nevada Test and Training Range. Its modern development began in 1955 when the CIA and Air Force chose the isolated site for Project AQUATONE and testing of the Lockheed U-2. The base quickly grew from a remote outpost into a major center for secret Cold War aviation programs, including OXCART, the Lockheed A-12, and early D-21 drone testing. Long shielded from public acknowledgment, Groom Lake became famous both for classified aircraft development and for the folklore, UFO stories, and tourism that grew around its secrecy.