Area 51 has been "exposed" for quite a while now. When they start making movies about it, you can be pretty sure it's no secret anymore. At one time, it was possible to hike the surrounding mountains and get pictures of the base directly, but that stopped about a decade ago when the governemnt finally realized what was happeneing and took over all of the surrounding mountains. Supposedly most of the installation are buried in the mountains and underground so they can't be seen from the air. Look up the name Bob Lazar, he claimed to be a MIT graduate and former employee there before leaving, then the government erased his identity when he went public.
Whatever used to be there, probably isn't there anymore since everybody seemed to know where Area 51 was. Supposedly, the new facility is hidden somewhere in New Mexico/Four corners region. However, they still keep Area 51 tightly guarded, don't even think of trying to sneak in. I know for a fact there are patrols watching you as soon as you enter anywhere near the property, and they sure the don't like it when you pretend to step over the border in the middle of the night.