Whatever its origins, the Inca turned the site into a small (5 square miles) but extraordinary city. Invisible from below and completely self-contained, surrounded by agricultural terraces sufficient to feed the population, and watered by natural springs, Machu Picchu seems to have been utilized by the Inca as a secret ceremonial city. Two thousand feet above the rumbling Urubamba river, the cloud shrouded ruins have palaces, baths, temples, storage rooms and some 150 houses, all in a remarkable state of preservation.