The ruined Inca city of Machu Picchu is located on two peaks in the Andes Mountains: Machu Picchu ("Old Peak") and Huayna Picchu ("Young Peak"). Known as the "Lost City of the Incas," Machu Picchu was uninhabited and forgotten for hundreds of years after the Spanish conquest of the Inca Empire. It is now a UNESCO World Heritage Site, one of the New Seven Wonders of the World, and of course a popular tourist attraction.
Why the Incas built this city up there on the top of the mountains in Peru is not known (or at least not agreed upon). Its buildings and monuments, including the Intihuatana or "hitching post of the sun," have led to suggestions of many interesting possibilities, such as a training place for Inca sun virgins. On the other hand, it has been suggested that it was a kind of country retreat for the wealthy! So, Machu Picchu rates right up there as one of the most mysterious and amazing places built in human history.