Area 51 is the name most commonly used for the Groom Lake airbase in Nevada. The US air force gives it the same appellation in some ways, since the whole of the site is numbered for convenience. However, Groom Lake is not a normal base: it’s a development and testing facility for new aircraft.

The site itself is ideal for this purpose as it’s out in the middle of nowhere and the dry lake bed locale provides enough space for very long landing strips, hangars and several other structures. It’s surrounded by mountains and the area is permanently off-limits to civilian and even military air traffic. People on foot are quickly removed by security forces and some have even been detained just for taking photographs from outside the exclusion area: the US military does not want anyone peeking here.

During World War II, the base was used for standard things like bombing practice and artillery training, but it wasn’t a major site. It was only in 1955 that the work on the U-2 spy plane (by Lockheed) needed somewhere to run tests and the site was chosen – again because of the ideal landing space and ease of securing the area. While the U2 was being tested, the larger area (the Nevada Test Site) was still being used for nuclear weapons testing, though Area 51 itself was not directly involved.

At the start of the 1960s, with the Cold War raging, the U-2 project was moving on into what eventually became the SR-71 Blackbird. Given the maintenance and flight requirements of that astounding piece of technical achievement, the base was extended – the runway had to be made much longer and new facilities were also built. The final remaining civilian enterprise in the area – a small mine – was closed and the whole valley and its surroundings became exclusively military.

Since the 1960s, Groom Lake has remained a development and testing site for the USAF. It has seen prototypes of the F-117 stealth fighter (and its predecessors) and also testing of that same airplane’s weaponry. RPVs (remotely piloted vehicles) have also been tested there by the CIA, as have variants on Russian MiG-17 and MiG-21 aircraft by the air force. The base now has seven runways, with the longest (at about 7,100 metres) being apparently closed.

Of course, one of the main reasons everyone knows about Area 51 is because of its place in conspiracy theory, the UFO subject and the fact that the US government barely even accepts that the place exists. It is, without a doubt, one of the most secretive facilities in the world. The security signs stating that trespassers will be met with deadly force only add to the cachet.

Given that the area is used for testing and developing new aircraft like the F-117, it is no surprise that strange flying phenomena are often seen. However, there are also many stories from people who have worked on the base and claim to have seen extraterrestrial craft, flying discs and even to have worked with aliens themselves. The Roswell incident has not helped discourage such claims. From the military’s and government’s point of view, this kind of publicity is not necessarily unwanted, as it covers whatever is really going on in the base, whether it’s extraterrestrial or not.

Other theories include the use of the base as a meeting place with aliens, weather control or teleportation device development and even activities related to the construction of a new world order by a shadowy one-world government. Of course, since the base looks like, well, a normal base, most of these theories rely on there being extensive underground facilities in which all that Black Projects technology is created and stored.