The FBI's digital reading room is an online library of once classified documents, telling a history that for many years did not exist.
Notorious criminals like "Machine Gun" Kelly and Ted Bundy would provide interesting reads but according to officials, the most popular document is on a UFO.
An unconfirmed report of the discovery of a flying saucer in New Mexico has received over a million page views since it was published two years ago.
The popular memo, was sent by FBI Washington field office chief Guy Hottel to then-Director J. Edgar Hoover on March 22, 1950.
In the document, surprising revelations are detailed from an unnamed 3rd party who claims that an Air Force official recovered three flying saucers in New Mexico.
The exact location is not mentioned but the memo goes on to say that "each one [saucer] was occupied by three bodies of human shape but only 3 feet tall, dressed in metallic cloth of a very fine texture."
Despite the claims, the FBI never investigated the incident because of the belief that it was third-hand information that could not be relied upon.
The informant's name is also blacked out on the document.
The memo has become a popular source for tabloids and UFO believer groups who claim it is direct evidence of a government cover-up.
The digital reading room contains around 6,700 public documents.
Whether you believe in UFO's or not, it certainly makes for good reading!