Hiram Bingham III Stuart McNairn whose descendants claim that they had already climbed to the ruins in 1906). Also the Cusco explorers Enrique Palma, Gabino Sanchez and Agustín Lizarraga are said to have arrived at the site in 1901. Bingham returned to Peru in 1912, 1914 and 1915 with the support of Yale and the National Geographic Society. In "The Lost City of the Incas" (1948), Bingham related how he came to believe that Machu Picchu housed a major religious shrine and served as a training center for religious leaders. Modern archaeological research has since determined that the site was not a religious
Machu Picchu more farmland to grow crops, and to steepen the slopes that invaders would have to ascend. The terraces reduced soil erosion and protected against landslides. Two high-altitude routes from Machu Picchu cross the mountains back to Cusco, one through the Sun Gate, and the other across the Inca bridge. Both could be blocked easily, should invaders approach along them. The site is roughly divided into an urban sector and an agricultural sector, and into an upper town and a lower town. The temples are in the upper town, the warehouses in the lower. The architecture is adapted to the mountains.