Area 51 has been one of the most secretive black spots in the history of the US military. The area adjoining the Nevada Test Site is practically inaccessible. But that very high level of secrecy has spawned all sorts of theories - more urban legends really - about what has been going on at Area 51. Author Annie Jacobsen has been researching this secret history and says that it was mainly a CIA and secret site for the Air Force to develop spyware. But she has also discovered a bizarre story about the origins of the space aliens who landed at Roswell, New Mexico.