Machu Picchu is a 15th-century Inca citadel, located in the Eastern Cordillera of southern Peru, on a 2,430-metre (7,970 ft) mountain ridge. It is located in the Machupicchu District within Urubamba Province above the Sacred Valley, which is 80 kilometres (50 mi) northwest of Cuzco. The Urubamba River flows past it, cutting through the Cordillera and creating a canyon with a tropical mountain climate.For most speakers of English or Spanish, the first 'c' in Picchu is silent. Most archaeologists believe that Machu Picchu was constructed as an estate for the Inca emperor Pachacuti (1438). Often mistakenly referred to as the "Lost City of the Incas", Machu Picchu was declared a Peruvian Historic Sanctuary in 1981 and a UNESCO World Heritage Site in 1983. In 2007, Machu Picchu was voted one of the New Seven Wonders of the World in a worldwide internet poll.