Machu Picchu Picchu a "historic 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". Bingham was a lecturer at Yale University, although not a trained archaeologist. In 1909, returning from the Pan-American Scientific Congress in Santiago, he travelled through Peru and was invited to explore the Inca ruins at Choqquequirau in the Apurímac
Machu Picchu prevent it from running down the mountain. Similar layering protected the large city center from flooding. Multiple canals and reserves provide water throughout the city that could be supplied to the terraces for irrigation and to prevent erosion and flooding. The Incas never used wheels in a practical way, although their use in toys shows that they knew the principle. The use of wheels in engineering may have been limited due to the lack of strong draft animals, steep terrain and dense vegetation. The approach to moving and placing the enormous stones remains uncertain, probably involving hundreds of men to