I believe that something did happen up at Rosweel in 47, and there was a huge cover-up, but it would be more than stupid to keep anything there now. What people see in the skies near the base is probably some military spy planes, just flown to keep public interest.
Area 51 is where the alien craft and bodies supposedly are now, but I think it is just there for the tourists. If people believe that something is there, they won't bother looking anywhere else.
In terms of aliens, I do not believe that the visitors our planet receives are in fact aliens. I think that they are human, evolved perhaps by several thousand years, and they have invented a form of time-travel.
I don't see how else a species could evolve on another world, and yet evolve to have 2 arms, 2 legs, a head, eys...etc. All sightnings are usually of humanoid creatures, so I see there being not many more possibilities.
Many people believe that we can't be alone, because of the vastness of space, and the millions of other habitable planets out there...but our appearence on earth happened through an amazingly slim chance, so there isn't much chance it could happen somewhere else....let alone it could happen so that they look so similar to us.
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