Machu Picchu was constructed around 1460, at the height of the Inca Empire. It was abandoned less than 100 years later. It is likely that most of its inhabitants were wiped out by smallpox before the Spanish conquistadores arrived in the area and there is no record of their having known of the remote city. Hiram Bingham, the credited discoverer of the site, along with several others, originally hypothesized that the citadel was the traditional birthplace of the Inca of the Virgins of the Suns .The central buildings of Machu Picchu uses 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. The Incas were among the best stone masons the world has seen, and many junctions in the central city are so perfect that it is said not even a knife blade fits between the stones.