Perhaps the most mystifying of all ancient sights is Pumapunku, part of a huge Bolivian temple and monument complex from around the 6th century.
Many archaeologists believe that, in its heyday, the site was incredibly fantastic, with elaborate ornamentation, polished metal, and intricate jewelry.
The blocks at the site — some weighing hundreds of tons — were so perfectly cut that they used to fit together. Could this mean that aliens built these structures?
