On Thursday, recently released declassified documents from the CIA concede to the existence of Area 51 in central Nevada.

The news came out after George Washington University’s National Security Archive received requested documents about the U-2 spy plane. They had asked for the papers through a public records request back in 2005 after receiving the same documents with mentions of Area 51 redacted back in 2002, USA Today reports.

The documents mention how the site came to be chosen, which at the time was merely a dilapidated landing strip near salt flats. The Washington Times notes, the documents mention the area in Nevada was selected because it was “an ideal site for testing the U-2 and training its pilots.”

The site was originally used in World War II as a gunnery range for pilots. It was chosen as the future site of Area 51 by then CIA project director Richard Bissell and Air Force officer Col. Osmund Ritlandt.

According to USA Today, Area 51 has in the past been partially acknowledged as existing by government officials. The site is often part of conspiracy theories about UFOs.

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