The ruins of Machu Picchu are one of the most beautiful ancient sites in the world. Ruins are located 2,430 metres (7,970 ft) above sea level on a mountain ridge above the Urubamba Valley in Peru, South America, which is 80 kilometres (50 mi) northwest of Cusco. Machu Picchu was built as an estate for the Inca emperor Pachacuti. Machu Picchu have been utilized as a secret ceremonial city, but one of primary functions was astronomical observatory. Officially Machu Picchu was rediscovered in 1911 by American explorer-historian Hiram Bingham.