MachuPicchu is a 15th century Incacitadel, located in the Eastern Cordillera of southern Peru, on a 2,430-metre (7,970 ft) mountain ridge. It is located in the Cusco Region, Urubamba Province, Machupicchu District, above the Sacred Valley, which is 80 kilometres (50 mi) northwest of Cuzco and through which the Urubamba River flows, cutting through the Cordillera and creating a canyon with a tropical mountain climate.

Most archaeologists believe that Machu Picchu was constructed as an estate for the Inca emperor Pachacuti (1438–1472). Often mistakenly referred to as the “Lost City of the Incas” (a title more accurately applied to Vilcabamba), it is the most familiar icon of Inca civilization. The Incas built the estate around 1450 but abandoned it a century later at the time of the Spanish Conquest. Although known locally, it was not known to the Spanish during the colonial period and remained unknown to the outside world until American historian Hiram Bingham brought it to international attention in 1911.

Machu Picchu was built in the classical Inca style, with polished dry-stone walls. Its three primary structures are the Intihuatana, the Temple of the Sun, and the Room of the Three Windows. Most of the outlying buildings have been reconstructed in order to give tourists a better idea of how they originally appeared. By 1976, thirty percent of Machu Picchu had been restored and restoration continues.

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.

History

Machu Picchu was built starting 1450–1460. Construction appears to date from two great Inca rulers, Pachacutec Inca Yupanqui (1438–1471) and Túpac Inca Yupanqui (1472–1493). There is a consensus among archaeologists that Pachacutec ordered the construction of the royal estate for himself, most likely after a successful military campaign. Though Machu Picchu is considered to be a “royal” estate, surprisingly, it would not have been passed down in the line of succession. Rather it was used for 80 years before being abandoned, seemingly because of the Spanish Conquests in other parts of the Inca Empire. It is possible that most of its inhabitants died from smallpox introduced by travelers before the Spanish conquistadors arrived in the area.

Construction

 The central buildings use the classical Inca architectural style of polished dry-stone walls of regular shape. The Incas were masters of this technique, called ashlar, in which blocks of stone are cut to fit together tightly without mortar.

The section of the mountain where Machu Picchu was built provided various challenges that the Incas solved with local materials. One issue was the seismic activity due to two fault lines. It made mortar and similar building methods nearly useless. Instead, the Inca mined stones from the quarry at the site, lined them up and shaped them to fit together perfectly, stabilizing the structures. Inca walls have many stabilizing features: doors and windows are trapezoidal, narrowing from bottom to top; corners usually are rounded; inside corners often incline slightly into the rooms, and outside corners were often tied together by “L”-shaped blocks; walls are offset slightly from row to row rather than rising straight from bottom to top.

Heavy rainfall required terraces and stone chips to drain rain water and prevent mudslides, landslides, erosion, and flooding. Terraces were layered with stone chips, sand, dirt, and topsoil, to absorb water and prevent it from running down the mountain. Similar layering protected the large city center from flooding. Multiple canals and reserves throughout the city provided water that could be supplied to the terraces for irrigation and to prevent erosion and flooding.

The Incas never used wheels in a practical way, although their use in toys shows that they knew the principle. The use of wheels in engineering may have been limited due to the lack of strong draft animals, steep terrain and dense vegetation. The approach to moving and placing the enormous stones remains uncertain, probably involving hundreds of men to push the stones up inclines. A few stones have knobs that could have been used to lever them into position; the knobs were generally sanded away, with a few overlooked