Deep in the Nevada desert lies a military base that is surrounded by so much official secrecy that the US government has even refused to acknowledge it exists. The base was built by the CIA and all pilots, ground crews and the staff have to retire from their original military departments and join the agency before taking residency on site.

As a CIA installation it operates independently of other government departments, To this day, signs at the entrance warn visitors they have no constitutional rights on site, and armed units guard the perimeter. It is the UFO's world's worst kept secret, and the area is now the pilgrimage point for alien watchers. This ladies and gentlemen is AREA 51.

Built in the 1950's around the Groom Lake Air Force base, and next to the Nevada atomic test range, Area 51 was a perfect site to carry out classified aircraft tests. It had a large flat surface perfect for laying runways, few local residents, and a highly unattractive reputation to new settlers due to the nearby nuclear pollution.

Initially it was built purely for testing the U2 spy plane, but the programme was such a success that all the United States secret aircraft were experimentally flown there.

The base grew in size, creating its own small community and the landing strip was increased to three miles long. The Blackbird and Stealth planes were developed on site, and countless unknown technologies are housed in the base's hanger.

Many people believe these technologies are, quite literally, from a different planet, and the base is actually a test zone and hiding site for alien aircraft. At night, strange lights are seen in the sky above the base, and many watchers believe the site hides enormous underground installations.

What do you think happens at Area 51? Does it house Alien Aircrafts? Why does the government refuse to acknowledge it?