I was confused because every one knew about Machu Picchu and I was like, what? So I decided to research it, and I found heaps of information...
Archaeologists have decided that the making of Machu Picchu began about 1450, and the city, which had about 200 stone structures, had people living in it for a century. But no one knows who lived at Machu Picchu and why it was built. Lots of professionals believe it was a royal estate and religious center for the Inca ruler and his family. Features such as private gardens and a bathroom, suggests that at least one very special or royal tribe or group of people stayed there. Experts say a population of about 300 people probably grew to 1,000 or something when the royal followers started living there too.
So that was helpful! I got alot of info from http://news.nationalgeographic.com/news/2002/04/0409_020417_machumap_2.html