• Machu Picchu, Peru Inca Sanctuary of Machu Picchu, 1450
  

The Incas started building the "estate" around 1400, 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. Since then, Machu Picchu has become an important tourist attraction. Most of the outlying buildings have been reconstructed in order to give tourists a better idea of what the structures originally looked like. By 1976, thirty percent of Machu Picchu had been restored. The restoration work continues to this day.

Since the site was never known to the Spanish during their conquest, it is highly significant as a relatively intact cultural site. Machu Picchu was declared a Peruvian Historical 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.

Machu Picchu was built in the classical Inca style, with polished dry stone walls. Its three primary structures are the Intihuatana (Hitching post of the Sun), the Temple of the Sun and the Room of the Three Windows. These are located in what is known by archaeologists as the Sacred District of Machu Picchu. In September 2007, Peru and Yale University almost reached an agreement regarding the return of artifacts which Yale has held since Hiram Bingham removed them from Machu Picchu in the early 20th century. In November 2010, a Yale University representative agreed to return the artifacts to a Peruvian university.

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 Pachacuti. 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] building[s] 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.

Although the citadel is located only about 80 kilometers (50 mi) 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.

As Bingham's excavations took place on Machu Picchu, local intellectuals began to oppose the operation of Bingham and his team of explorers. Though local institutions were initially enthused at the idea of the operation supplementing Peruvian knowledge about their ancestry, the team began to encounter accusations of legal and cultural malpractice. Local landowners began to demand payments of rent from the excavation team, and rumors arose about Bingham and his team stealing artifacts and smuggling them out of Peru through the bordering country of Bolivia. These accusations worsened when the local press caught wind of the rumors and helped to discredit the legitimacy of the excavation, branding the practice as harmful to the site and claiming that local archaeologists were being deprived of their rightful knowledge about their own history because of the intrusive excavations of the American archaeologists. By the time Bingham and his team left Machu Picchu locals began forming coalitions in order to defend their deserved ownership of Machu Picchu and its cultural remains, while Bingham claimed the artifacts ought to be studied by experts in American institutions, an argument that still exists today.

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.

Although Bingham was the first person to bring word of the ruins to the outside world, previous outsiders were said to have seen them. Simone Waisbard, a long time researcher of Cusco, claims that Enrique Palma, Gabino Sánchez and Agustín Lizárraga left their names engraved on one of the rocks at Machu Picchu on 14 July 1901. In 1904, an engineer named Franklin supposedly spotted the ruins from a distant mountain. He told Thomas Payne, an English Christian missionary living in the region, about the site, Payne's family members claim. They also report that in 1906, Payne and fellow missionary Stuart E. McNairn (1867 - 1956) climbed up to the ruins.

The site may have been discovered and plundered in 1867 by a German businessman, Augusto Berns. There is some evidence that a German engineer, J. M. von Hassel, arrived earlier. Maps found by historians show references to Machu Picchu as early as 1874.

Machu Picchu lies in the southern hemisphere, 13.164 degrees south of the equator. It is 80 kilometers northwest of Cusco, on the crest of the mountain Machu Picchu, located about 2,450 meters (8,040 ft) above mean sea level, over 1,000 meters (3,300 ft) lower than Cusco, which has an altitude of 3,600 meters (11,800 ft). As such, it had a milder climate than the Inca capital. It is one of the most important archaeological sites in South America, one of the most visited tourist attractions in all of Latin America and the most visited tourist attraction in Peru.

The year at Machu Picchu is divided between wet and dry seasons, with the majority of annual rain falling from October through to April. It can rain at any time of the year.

Machu Picchu is situated above a loop of the Urubamba River, which surrounds the site on three sides, with cliffs dropping vertically for 450 meters (1,480 ft) to the river at their base. The area is subject to morning mists rising from the river. The location of the city was a military secret, and its deep precipices and steep mountains provided excellent natural defenses. The Inca Bridge, an Inca rope bridge, across the Urubamba River in the Pongo de Mainique, provided a secret entrance for the Inca army. Another Inca bridge was built to the west of Machu Picchu, the tree trunk bridge, at a location where a gap occurs in the cliff that measures 6 meters (20 ft). It could be bridged by two tree trunks, but with the trees removed, there was a 570 meters (1,870 ft) fall to the base of the cliffs.

The city sits in a saddle between the two mountains Machu Picchu and Huayna Picchu, with a commanding view down two valleys and a nearly impassable mountain at its back. It has a water supply from springs that cannot be blocked easily, and enough land to grow food for about four times as many people as ever lived there. The hillsides leading to it have been terraced, not only to provide more farmland to grow crops, but to steepen the slopes which invaders would have to ascend. The terraces reduced soil erosion and protected against landslides. Two high altitude routes from Machu Picchu go across the mountains back to Cusco, one through the sun gate, and the other across the Inca bridge. Both could be blocked easily, should invaders approach along them. Regardless of its original purpose, it is strategically located and readily defended.

The ruins of Machu Picchu are divided into two main sections known as the Urban and Agricultural Sectors, divided by a wall. The Agricultural Sector is further subdivided into Upper and Lower sectors, while the Urban Sector is split into East and West sectors, separated by wide plazas.

The central buildings of Machu Picchu 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. Many junctions in the central city are so perfect that it is said not even a blade of grass fits between the stones.

Some Inca buildings were constructed using mortar, but by Inca standards this was quick, shoddy construction, and was not used in the building of important structures. Peru is a highly seismic land, and mortar-free construction was more earthquake - resistant than using mortar. The stones of the dry - stone walls built by the Incas can move slightly and resettle without the walls collapsing.

Inca walls had numerous design details that helped protect them against collapsing in an earthquake. Doors and windows are trapezoidal and tilt inward from bottom to top; corners usually are rounded; inside corners often incline slightly into the rooms; and "L" shaped blocks often were used to tie outside corners of the structure together. These walls do not rise straight from bottom to top, but are offset slightly from row to row.

The Incas never used the wheel in any practical manner. Its use in toys demonstrates that the principle was well known to them, although it was not applied in their engineering. The lack of strong draft animals, as well as steep terrain and dense vegetation issues, may have rendered the wheel impractical. How they moved and placed the enormous blocks of stones remains a mystery, although the general belief is that they used hundreds of men to push the stones up inclined planes. A few of the stones still have knobs on them that could have been used to lever them into position; it is believed that after the stones were placed, the Incas would have sanded the knobs away, but a few were overlooked.

The space is composed of 140 structures or features, including temples, sanctuaries, parks, and residences that include houses with thatched roofs. There are more than one hundred flights of stone steps — often completely carved from a single block of granite — and numerous water fountains. These were interconnected by channels and water drains perforated in the rock that were designed for the original irrigation system. Evidence suggests that the irrigation system was used to carry water from a holy spring to each of the houses in turn.

According to archaeologists, the urban sector of Machu Picchu was divided into three great districts: the Sacred District, the Popular District to the south, and the District of the Priests and the Nobility.

Located in the first zone are the primary archaeological treasures: the Intihuatana, the Temple of the Sun and the Room of the Three Windows. These were dedicated to Inti, their sun god and greatest deity. The Popular District, or Residential District, is the place where the lower-class people lived. It includes storage buildings and simple houses.

The royalty area, a sector for the nobility, is a group of houses located in rows over a slope; the residence of the Amautas (wise persons) was characterized by its reddish walls, and the zone of the Ñustas (princesses) had trapezoid - shaped rooms. The Monumental Mausoleum is a carved statue with a vaulted interior and carved drawings. It was used for rites or sacrifices.

As part of their road system, the Incas built a road to the Machu Picchu region. Today, tens of thousands of tourists walk the Inca Trail to visit Machu Picchu each year. They acclimate at Cusco before starting on the two- to four day journey on foot from the Urubamba valley, walking up through the Andes mountain range to the isolated city.

The people of Machu Picchu were connected to long distance trade, as shown by non-local artifacts found at the site. As an example, Bingham found unmodified obsidian nodules at the entrance gateway. In the 1970s, Burger and Asaro determined that these obsidian samples were from the Titicaca or Chivay obsidian source, and that the samples from Machu Picchu showed long distance transport of this obsidian type in pre-Hispanic Peru.

The Guardhouse is a three - sided building, with one of its long sides opening onto the Terrace of the Ceremonial Rock. The three - sided style of Inca architecture is known as the wayrona style.

In 2005 and 2009, the University of Arkansas made detailed laser scans of the entire Machu Picchu site and of the ruins at the top of the adjacent Huayna Picchu mountain. The university has made the scan data available online for research purposes.

The Intihuatana stone is one of many ritual stones in South America. These stones are arranged to point directly at the sun during the winter solstice. The name of the stone (coined perhaps by Bingham) is derived from the Quechua language: inti means "sun", and wata- is the verb root "to tie, hitch (up)" (huata- is simply a Spanish spelling). The Quechua -na suffix derives nouns for tools or places. Hence inti watana is literally an instrument or place to "tie up the sun", often expressed in English as "The Hitching Post of the Sun". The Inca believed the stone held the sun in its place along its annual path in the sky. At midday on November 11 and January 30 the sun stands almost above the pillar, casting no shadow at all. On June 21 the stone is casting the longest shadow on his southern side and on December 21 a much shorter one on his northern side. Researchers believe that it was built as an astronomic clock or calendar.

Machu Picchu is a UNESCO World Heritage Site. Since its discovery in 1911, a growing number of tourists visit Machu Picchu, reaching 400,000 in 2000. As Peru's most visited tourist attraction and major revenue generator, it is continually threatened by economic and commercial forces. In the late 1990s, the Peruvian government granted concessions to allow the construction of a cable car and development of a luxury hotel, including a tourist complex with boutiques and restaurants. Many people protested against the plans, including members of the Peruvian public, international scientists, and academics, as they were worried that the greater numbers of visitors would pose a tremendous physical burden on the ruins. Many protested a plan to build a bridge to the site as well. A no-fly zone exists above the area. UNESCO is considering putting Machu Picchu on its List of World Heritage in Danger.

In July 2011, the Dirección Regional de Cultura Cusco (DRC) introduced new entrance rules to the citadel of Machu Picchu. The tougher entrance rules were a measure to reduce the impact of tourism on the site. Entrance was limited to 2,500 visitors per day, and entrance to Huayna Picchu (within the citadel) was further restricted to 400 visitors per day, in two allocated time slots at 7am and 10am.

In May 2012, however, a team of UNESCO conservation experts called on Peruvian authorities to take "emergency measures" to further stabilize the site’s buffer zone and protect it from pressure as a result of tourism related development, particularly in the nearby town of Aguas Calientes, which has seen rapid development.

In 1912 and 1914-15, Bingham excavated treasures from Machu Picchu — ceramic vessels, silver statues, jewelry, and human bones — and took them from Peru to Yale University in the United States for further study, supposedly for a period of 18 months. Yale has retained the artifacts until now, under the argument that Peru did not have the infrastructure or proper conditions to take care of the pieces.

Eliane Karp, an anthropologist who is married to the former Peruvian President Alejandro Toledo, accused Yale of profiting from Peru's cultural heritage by claiming title to thousands of pieces removed by Bingham. Many have been on display at Yale's Peabody Museum since their removal. Yale returned some of the artifacts to Peru, but the university kept the remainder, claiming its position was supported by federal case law involving Peruvian antiquities.

On 19 September 2007, the Courant reported that Peru and Yale had reached an agreement regarding the requested return of the artifacts. The agreement includes sponsorship of a joint traveling exhibition and construction of a new museum and research center in Cusco about which Yale will advise Peruvian officials. Yale acknowledges Peru's title to all the excavated objects from Machu Picchu, but Yale will share rights with Peru in the research collection, part of which will remain at Yale as an object of continuing study.

On 19 June 2008, National Geographic Society's vice president Terry Garcia was quoted by the daily publication, La República. "We were part of this agreement. National Geographic was there, we know what was said, the objects were lent and should be returned."

On 21 November 2010, Yale University agreed in principle to the return of the controversial artifacts to their original home in Peru.

La Casa Concha (The Shell House) located close to Cusco's colonial center was to be the permanent site where the Yale University artifacts would be exhibited. Owned by the National University of San Antonio Abad Del Cusco, La Casa Concha was also to feature a study area for local and foreign students.

In August 2012, the Peruvian president announced plans to build a new international airport in Cusco replacing function of the current small domestic airport to boost tourism with £290 million investment.