Area 51 was a top secret aircraft testing facility. It was also used as the location to test Lunar drones and a training ground for Astronauts to learn how to drive their buggys on the moon. They tested nuclear devices on the dried out lakebed next to the facility as well. There are no aliens there, the government would never allow something as groundbreaking as aliens to be kept in such a facility, as the public knows about the facility as well as its whereabouts in general. Those who work there either take a private Boeing 747 into the facility, or they live in one of the many housing structures there. That is it.