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 an Inca grass rope bridge, across the Urubamba River in the Pongo de Mainique, provided a secret entrance for the Inca army. Another Inca bridge was built to the west of Machu Picchu, the tree-trunk bridge, at a location where a gap occurs in the cliff that measures . The city sits in a saddle between the two mountains Machu Picchu and Huayna Picchu, with a commanding view down two valleys and a nearly impassable mountain at its back. It has a water supply from springs that cannot be blocked easily. The hillsides leading to it were terraced, to provide