WASHINGTON, August 16 (RIA Novosti) – For decades the mysterious Area 51 site in the Nevada desert has been the subject of countless conspiracy theories, including the existence of extraterrestrials, alien autopsies and whether the site even existed at all. But newly declassified Central Intelligence Agency (CIA) documents finally acknowledge that Area 51 did indeed exist and reveal that it was used as a base to test U-2 and other spy planes.

The more than 400 page CIA report about Area 51 and spy planes is contained in “The Central Intelligence Agency and Overhead Reconnaissance: The U-2 and Oxcart Programs, 1954-1974,” which was released Thursday by George Washington University’s National Security Archive after it obtained the report in response to a Freedom of Information request filed in 2005.

The high altitude U-2 spy planes were used by the United States around the world, including over the Soviet Union during the Cold War.

The CIA report also acknowledges British participation in the U-2 program and the National Security Archive says the report’s authors note that “President Dwight Eisenhower viewed British participation ‘as a way to confuse the Soviets as to sponsorship of particular overflights’ as well to spread the risk of failure.”

The report details how officials involved in the spy plane project flew over the Nevada desert in a small plane in April 1955 looking for secret test sites. “They spotted what appeared to be an airstrip by a salt flat known as Groom Lake, near the northeast corner of the Atomic Energy Commission’s Nevada Proving Ground.”

The officials concluded that it would be “an ideal site for testing the U-2 and training its pilots.”

“President Eisenhower also approved the addition of this strip of wasteland, known by its map designation as Area 51, to the Nevada Test Site,” the report said.

The U-2 planes flew at an altitude of 70,000 feet (21,336 meters), which according to the CIA report, led to “a tremendous increase in reports of unidentified flying objects (UFOs).”

The first US military planes arrived at Area 51 on July 25, 1955 and the first test flight took place on Aug. 4 of that year, according to the Las Vegas Sun.

The CIA report “marks an end of official secrecy about the facts of Area 51,” Jeffrey Richelson, a senior fellow with the National Security Archive, told the Las Vegas Sun.