Area 51 is a real place but it holds retired and battle damaged aircraft until they are needed elsewhere, the alien rumor started several years ago when an experimental blimp went up in flames and some local thought it looked like a UFO. In short, they don't have aliens or alien space craft there.
They probably don't have aliens but they probably have extremely top military secrets. They probably have very dangerous weapons there too. One thing I do know is that they have USAF aircrafts. They are also testing new military planes their.
I wound up at the Area 51 gate by accident, years ago. See my comment under LubedUpUnicorn's answer. Locals said the place was a lot busier decades ago, because a lot more top-secret stuff was being tested there. Since then, there were too many UFO groupies flocking to the place and nosing around. So, now it's mostly storage and testing of some highly-classified plane and equipment testing. It's an important detached area of Edwards Airforce base, still. But, these days, any super-super-secret flight equipment testing is done far away at way less famous locations. -- And Shinypate1 is right. They are one of the main bases doing radioactive soil and groundwater tests because of all the underground testing that was (and perhaps still is, in equipment terms) done there. -- But the locals love that they're still making $$ off UFO-curious tourists. Aliens at Area 51? Uhhhhhh .... Dunno. You could always go and stay at the Little A'Le'Inn (B&B and restaurant) in Rachel, Nevada (pop. about 60, I think), and they'll be happy to tell you more! --They might even know of some tour guides who can take you to get a binoculars-eye view of Area 51, from a distance. Make a cool vacation out of it. What the heck, eh? :D
If all of you wanna know, just go to Infowars.com or Prison planet. You have now idea of the corruption in Govt, FDA, Monsanto and all the big oil companies. The Illuminati is alive and well in the USA. Most Americans and Canadians are not people, they're sheeple and will believe everything they see on CNN.