Debunking many conspiracy theories, a massive 355-page declassified report details the birth of Area 51 and the U-2 spy planes developed and tested there.When U-2 spy planes first soared over Nevada in 1955, they flew higher than any other plane ever: 60,000 feet. The development and construction of the vessels were part of a top-secret CIA operative in the remote desert of Nevada known as Area 51. When people who lived nearby saw the sleek planes -- far above, glinting in the sun -- they had no idea what they were. And naturally, it became widely believed they were UFOs carrying aliens. Many of the details and history around Area 51 and U-2 planes were recently declassified by the CIA and revealed to the public on Thursday. This information comes via a 355-page report (PDF) titled "The Central Intelligence Agency and Overhead Reconnaissance: The U-2 and OXCART Programs, 1954 - 1974," which the National Security Archive got the CIA to declassify under the Freedom of Information Act. While scant particulars on Area 51 have been discovered over the years through other declassified reports and books that contained interviews with people involved in the operative, this new report is the first time the government has openly referred to Area 51 as a government facility, according to Foreign Policy.