Lost city Inca site situated on a mountain ridge above the Urubamba Valley in Peru. Often referred to as the "Lost City of the Incas", it is perhaps the most familiar icon of the Inca World. Machu Picchu was built around 1450, at the height of the Inca Empire. It was abandoned just over 100 years later, in 1572, as a belated result of the Spanish Conquest. It is possible that most of its inhabitants died from smallpox introduced by travelers before the Spanish conquistadors arrived in the area. In 1911, Melchor Arteaga led the explorer Hiram Bingham to Machu Picchu, which
Machu Picchu more farmland to grow crops, and to steepen the slopes that invaders would have to ascend. The terraces reduced soil erosion and protected against landslides. Two high-altitude routes from Machu Picchu cross the mountains back to Cusco, one through the Sun Gate, and the other across the Inca bridge. Both could be blocked easily, should invaders approach along them. 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, the warehouses in the lower. The architecture is adapted to the mountains.