Puma Punku

A lot of these alien shows are pretty far fetched, however this episode was one of the most compelling that I saw.  I do still think that there is a chance that we underestimate the engineering and constructions abilities of the ancient cultures, not to mention the amount of time they had to build these things, but the fact that they went so far out of their way to build up above the tree line in the thin air is pretty intriguing.