above the Sacred Valley, which is 80 kilometres (50 mi) northwest of Cuzco and through which the Urubamba River flows.
Most archaeologists believe that Machu Picchu was constructed as an estate for the Inca emperor Pachacuti (1438–1472).
However, the terraces were not perfect, as studies of the land show that there were landslides that happened during the construction of Machu Picchu.
It can still be seen where the terraces were shifted by landslides and then stabilized by the Inca as they continued to build around the area.
On top of the gravel was a layer of mixed sand and gravel packed together, with rich topsoil covering all of that.
It was proven that the topsoil was probably moved from the valley floor to the terraces because it was much more rich than the soil higher up the mountain.
The conquistadors had notes of a place called Piccho, although no record of a Spanish visit exists.
The types of sacred rocks defaced by the conquistadors in other locations are untouched at Machu Picchu.
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.
The terraces received so much rain that they were built specifically to allow for ample drainage of the extra water.
Excavation and soil analyses done by Kenneth Wright in the 90's showed that the terraces were built in layers, with a bottom layer of larger stones covered by loose gravel.
Its three primary structures are the Intihuatana, the Temple of the Sun, and the Room of the Three Windows.