Area 51, a top secret military installation for testing unacknowledged, or black, projects, lies in a desert valley northwest of Las Vegas. During the Cold War, CIA and Air Force officials chose this remote location to shield such efforts from foreign spies and US citizens. Although the base has been known by many names—Paradise Ranch, Watertown, and Dreamland, among others—the designation “Area 51” has taken root most deeply in the public imagination. Since 1955, it has grown from a temporary camp into a national test facility supporting nearly 2,000 military and civilian workers and dozens of projects, including aircraft capable of cruising at Mach 3 and stealth airplanes that are virtually invisible to radar. Although secrecy surrounding Area 51 spawned rumors of UFOs and reverse-engineered alien spacecraft, declassified photographs provide a rare glimpse into the true nature of America's most famous secret base.