Area 51

Area 51 is a military base in Nevada, and a former testing ground for experimental government aircraft and extraterrestrial phenomena. The area 51 appears to contain some alien technology, like a captured flying saucer re-captured by aliens, but crashed in California.

Appearances
Area 51 is mentioned in Fallout, as a print on a flying saucer in the alien ship special encounter. It was to appear as a location in Fallout 2 but was cut for the final version of the game, inhabited by a group of scientists.