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(USA Today) -- After years of government denials, the CIA is officially acknowledging in newly declassified documents the existence of Area 51, the mysterious site in central Nevada that has spawned top-secret tools, weapons and not a few UFO conspiracies.

PHOTOS |CIA: Area 51 exists

George Washington University's National Security Archive obtained a CIA history of the U-2 spy plane program through a public records request and released it Thursday.

National Security Archive senior fellow Jeffrey Richelson reviewed the history in 2002, but all mentions of Area 51 had been redacted.

Richelson says he requested the history again in 2005 and received a version a few weeks ago with mentions of Area 51 restored.

Officials have already acknowledged in passing the existence of the facility in central Nevada where the government is believed to test intelligence tools and weapons.