Machu Picchu, "Old Peak" is a 15th-century Inca site located 2,430 metres above sea level. Machu Picchu is located in the Cusco Region of Peru, South America. It is situated on a mountain ridge above the Urubamba Valley in Peru, which is 80 kilometres northwest of Cusco and through which the Urubamba River flows. Most archaeologists believe that Machu Picchu was built as an estate for the Inca emperor Pachacuti (1438–1472). Often referred to as the "City of the Incas", it is perhaps the most familiar icon of Inca civilization. The Incas built the estate around 1450, but abandoned it as an official site for the Inca rulers a century later at the time of the Spanish Conquest. Although known locally, it was unknown to the outside world before being brought to international attention in 1911 by the American historian Hiram Bingham.