The US military built Area 51 in 1955 specifically to test the secret U-2 spy plane.

In 1955, the US government set up the base near Groom Lake, a dry lake bed in the Nevada desert. They needed a hidden place to test the U-2, a high-altitude spy plane designed to fly over the Soviet Union. For decades, the government kept the base a complete secret. They only officially admitted it existed in 2013 after a public records request.