From technology to terror – some of the best kept military and CIA secrets that were declassified

1. Project 1794

Project 1794 was launched in the 1950s when engineers built a disc-shape vehicle that could travel at a top speed of Mach 4 (four times the speed of sound), at an altitude of 100,000 feet (30,480 meters). The project cost over $3 million, worth more than $26 million today. The project was canceled in December 1961 when tests found the design unstable. The documents were declassified in late 2012 by the U.S. Air Force.

2. Project MK-ULTRA

The CIA initiated Project MK-ULTRA – a confidential and illegal research program to study mind-control systems in humans. They tested the effects of biological agents, hypnosis and drugs, including LSD and barbiturates.

Richard Helms, CIA director in 1973, ordered the destruction of all documents from Project MK-ULTRA. However, a formal investigation was initiated some years later.

3. Area 51

Area 51, an isolated tract near Groom Lake in the Nevada desert, has been very popular with conspiracy theorists and UFO-enthusiasts. Area 51 was often associated with paranormal activities.

Declassified CIA documents confirmed the existence of Area 51 in July 2013, and that it was used for testing spy planes, including the U-2 reconnaissance aircraft.