Hello Lindsay, Not sure what documentaries you sawa but there was a lot of discussion about this from a series of books in the 1980's I think (perhaps earlier) where Erichvon Daniken claimed that the markings on the Nazca Plains showed pictures of astronauts and argued that this implied that astronauts, presumably extra-terrestrial, had visited ancient south america. The books were called something like "In Search of Ancient Gods". I can't remember the details but I think these were pretty heavily discredited. The scales were not quite as quoted and a few other discrepancies.

Cheers - David