The Incas, in contrast to the Maya, had no written language, and no European visited the site until the 19th century, so far as is known. There are, therefore, no written records of the site while it was in use. The names of the buildings, their supposed uses, and their inhabitants are all the product of modern archeologists, on the basis of physical evidence, including tombs at the site.
Most recent archaeologists believe that Machu Picchu was constructed as an estate for the Inca emperor Pachacuti (1438–1472). Often referred to as the "Lost City of the Incas", 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. According to the new AMS radiocarbon dating, it was occupied from c. 1420–1532. Historical research published in 2022 claims that the site was probably called Huayna Picchu by the Inca, as it exists on the smaller peak of the same name.
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 visitors a better idea of how they originally appeared. By 1976, 30% of Machu Picchu had been restored and restoration continues.
The site is roughly divided into an urban sector and an agricultural sector, and into an upper town and a lower town. The temples are in the upper town, and the warehouses are in the lower. The architecture is adapted to the mountains. Approximately 200 buildings are arranged on wide parallel terraces around an east-west central square. The various compounds, called kanchas, are long and narrow in order to exploit the terrain. Sophisticated channeling systems provided irrigation for the fields. Stone stairways set in the walls allowed access to the different levels across the site. The eastern section of the city was probably residential. The western, separated by the square, was for religious and ceremonial purposes. This section contains the Torreón, the massive tower which may have been used as an observatory.
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.
According to Wikipedia