Some believe that an alien spacecraft crashed in Roswell, N.M., and that the government shipped the wreckage and a body to Area 51 for examination and study. Others claim the facility has underground levels and tunnels connecting it to other secret sites, and that it contains warehouses full of alien technology and even living alien specimens.
A few go even further, theorizing that the aliens are actually the ones running the show and their goal is to create a human-alien hybrid (the aliens seem to have lost the ability to reproduce on their own). Stories cast the aliens in roles ranging from benevolent visitors to evil overlords who subsist on a paste made from ground-up human bits. Air Force representatives have publicly denied that aliens have anything at all to do with Area 51, but that seems to have only strengthened conspiracy theorists' wilder suggestions.
On June 24, 1947, Kenneth Arnold reported sighting nine objects, flying in a V formation, while piloting his private plane over Washington state. He said the objects flew like a saucer would if you skipped it across the water, and the term "flying saucer" was born [source: History].
In July 1947, an airborne object crashed on a ranch near Roswell. The Roswell Army Air Field issued a press release from Gen. William "Butch" Blanchard, stating it had recovered the remains of an unidentified flying object or UFO. The Army quickly retracted the statement, saying it was not a flying disc at all but a weather balloon. But the original statement had already run in several papers [source: History, The Roswell Files]. The incident was largely forgotten until the 1970s when nuclear physicist Stanton T. Friedman wrote a book arguing that the crash was a result of extraterrestrial activity.
In the 1990s, declassified documents said that the object recovered at Roswell was actually a balloon created for a surveillance program called Project Mogul. The weather balloon story was a cover for this secret project [source: McAndrew]. Of course, UFO believers say that the spy balloon story is also a cover, and that the Army really did recover an alien craft.