NOVA: Secrets of Lost Empires - Inca

This television documentary is one in a four-part series that tests theories regarding the architectural achievements of ancient civilizations. Based on archaeological evidence, scientists conduct physical reconstructions of these theories to see if they would have actually worked. The series is co-produced by Nova and BBC. In this installment, they test theories regarding the ancient world of Machu Picchu in Peru. Topics covered in this episode include present-day people building bridges out of grass fiber and how the ancient Incas built walls made of huge blocks of stone with such precision that each block fits tightly with the next.