The local people knew of the ruins long ago. In 1911, the guide Melchor Arteaga led Professor Hiram Bingham to Machu Picchu. Bingham returned in 1914 with the support of Yale University and the National Geographic Society and since then, Machu Picchu has been known as the "Lost City of the Incas", an initial confusion with Old Vilcabamba (amazing ruins that require a 2 days adventurous expedition from Cusco City).

The Citadel is believed to have been fundamentally for religious purposes. Bingham found a cemetery exclusively for women, which led him to believe it was an immense monastery of acllas (young woman) an a retreat and resting place for the Cusco sovereign. Its construcction possibly dates to the times of Tupac Inca Yupanqui, the final era of the Inca empire.

The Machu Picchu Historical Sanctuary (32,492 hectares 80,255 acres) is a natural reserve which UNESCO declared a World Cultural and Natural Heritage Site in 1983.