Machu Picchu was built around 1460 by a group led by Pachuacuo Onca Yupanqui, one of the most effective Incan rulers. It is thought that it was to be a royal estate and religious retreat; it contains residences as well as various public buildings. The structures are built with granite blocks cut with stone or bronze tools and smoothed with sand. The blocks fit together well; no mortar was used. The walls slant a bit probably to make the structures more stable. They used thatched roofs and some have been reconstructed. Corn and potatoes were grown on the terraced gardens.
About 90 years later it was abandoned; perhaps because many people died from small pox but also they were trying to protect it from the Spanish invasion. It was clearly built in a hard to find and reach place that could be defended. They obliterated the trail to it when they left and the Spaniards never did find it. Some of the locals knew where it was and helped Hiram Bingham find it in 1911.
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A 25 sec video tour
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