Machu Picchu was built around 1450, at the height of the Inca Empire. The construction of Machu Picchu appears to date from the period of the two great Incas, Pachacutec Inca Yupanqui (1438-71) and Tupac Inca Yupanqui (1472-93). It was abandoned just over 100 years later, in 1572, as a belated result of the Spanish Conquest. It is possible that most of its inhabitants died from smallpox introduced by travelers before the Spanish conquistadors arrived in the area.The latter had notes of a place called Piccho, although there is no record of the Spanish having visited the remote city. The types of sacred rocks defaced by the conquistadors in other locations are untouched at Machu Picchu.
Hiram Bingham theorized that the complex was the traditional birthplace of the Incan "Virgins of the Suns". More recent research by scholars such as John Howland Rowe and Richard Burger, has convinced most archaeologists that Machu Picchu was an estate of the Inca emperor Pachacute. In addition, Johan Reinhard presented evidence that the site was selected because of its position relative to sacred landscape features such as its mountains, which are purported to be in alignment with key astronomical events important to the Incas.
Johan Reinhard believes Machu Picchu to be a sacred religious site. This theory stands mainly because of where Machu Picchu is located. Reinhard calls it "sacred geography" because the site is built on and around mountains that hold high religious importance in the Inca culture and in the previous culture that occupied the land. At the highest point of the mountain in which Machu Picchu was named after, there are “artificial platforms and these had a religious function, as is clear from the Inca ritual offerings found buried under them”. These platforms also are found in other Incan religious sites. The site’s other stone structures have finely worked stones with niches and, from what the “Spaniards wrote about Inca sites, we know that these types of buildings were of ritual significance”. This would be the most convincing evidence that Reinhard points out because this type of stylistic stonework is only found at the religious sites so it would be natural that they would exist at this religious site. Another theory maintains that Machu Picchu was an Inca llaqta, a settlement built to control the economy of conquered regions. Yet another asserts that it may have been built as a prison for a select few who had committed heinous crimes against Inca society. An alternative theory is that it is an agricultural testing station. Different types of crops could be tested in the many different micro-climates afforded by the location and the terraces; these were not large enough to grow food on a large scale, but may have been used to determine what could grow where. Another theory suggests that the city was built as an abode for the deities, or for the coronation of kings.
View of the city of Machu Picchu in 1911 showing the original ruins before modern reconstruction work began.Although the citadel is located only about 80 kilometers from Cusco, the Inca capital, the Spanish never found it and consequently did not plunder or destroy it, as they did many other sites. Over the centuries, the surrounding jungle grew over much of the site, and few outsiders knew of its existence.
On 24 July 1911, Hiram Bingham announced the discovery of Machu Picchu to scholars. As an American historian employed as a lecturer at Yale University, Bingham had been searching for the city of Vilcabamba, the last Inca refuge during the Spanish conquest. He had worked for years in previous trips and explorations around the zone. Pablito Alvarez, a local 11 year-old Quechua boy, led Bingham up to Machu Picchu.Some Quechuas lived in the original structures at Machu Picchu.
Bingham started archaeological studies and completed a survey of the area. He called the complex "The Lost City of the Incas", which was the title of his first book. Bingham made several more trips and conducted excavations on the site through 1915, collecting various artifacts which he took back to Yale. He wrote a number of books and articles about the discovery of Machu Picchu.
The site received significant publicity after the National Geographic Society devoted their entire April 1913 issue to Machu Picchu. In 1981 Peru declared an area of 325.92 square kilometers surrounding Machu Picchu as a "Historical Sanctuary". In addition to the ruins, the sanctuary includes a large portion of the adjoining region, rich with the flora and fauna of the Peruvian Yungas and Central Andean wet puna ecoregions.
In 1983 UNESCO designated Machu Picchu a World Heritage Site, describing it as "an absolute masterpiece of architecture and a unique testimony to the Inca civilization".
The World Monuments Fund placed Machu Picchu on its 2008 Watch List of the 100 Most Endangered Sites in the world because of environmental degradation. This has resulted from the impact of tourism, uncontrolled development in the nearby town of Aguas Calientes, which included a poorly sited tram to ease visitor access, and the construction of a bridge across the Vilcanota River, which is likely to bring even more tourists to the site, in defiance of a court order and government protests against it.