Area 51 - the dry salt flat north of Las Vegas where the government carried out some of its most secret testing and spywork during the Cold War doesn't hold many secrets. But the Central Intelligence Agency has finally acknowledged that the dark space exists. The agency recently declassified a 1992 history of the U-2 spy plane and in doing so it explicitly, if inadvertently, acknowledged that it had set up the base to build and test the most secret flying machines of the 1950s and 1960s.
Jeffrey Richelson, Senior Analyst, National Security Archive