The Temple of the Sun, also known as the Torreon, is a wonderful, semicircular, walled, tower-like temple displaying some of Machu Picchu's finest granite stonework. Constructed to incorporate polyhedrons and trapezoidal window niches, the temple's carved steps and smoothly joined stone blocks also fit neatly into the existing relief of a natural boulder that served as some kind of altar and also marks the entrance to a small cave. A window off this temple provides views of both the June solstice sunrise and the constellation of the Pleiades, which rises from here over the nearby peak of Huayna Picchu. The Pleiades are still a very important astronomical Andean symbol relating to crop fertility: locals use the constellation as a kind of annual signpost in the agricultural calendar, giving information about when to plant crops and when the rains will come.
Machu Picchu is a 15th-century Inca site located 2,430 metres above sea level on a mountain ridge above the Urubamba Valley. Most archaeologists believe that Machu Picchu was built as an estate for the Inca emperor Pachacuti (1438–1472). Often referred to as "The Lost City of the Incas", it is perhaps the most familiar icon of the Inca World.
The Incas started building the "estate" around AD 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.
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.