Separating fact and fiction in Inca history is impossible, because virtually all the sources available are Spanish accounts of stories that had already been vetted by the Inca emperors to highlight their own heroic roles. Imagine a history of modern Iraq written by Dick Cheney and based on authorized biographies of Sadam Hussein published in Arabic, and you'll get some idea of what historians face.
Mark Adams, Turn Right at Machu Picchu: Rediscovering the Lost City One Step at a Time
humor, machu-picchu, peru, travel