Machu Picchu was never lost to the people living around it, only to the university expedition that made it famous.
A guided arrival
Hiram Bingham, a Yale lecturer searching for a different lost city, was led to the ruins on 24 July 1911 by a local farmer, Melchor Arteaga, who already knew the site, and a boy from a family farming terraces within the ruins themselves. Bingham's expedition removed thousands of artefacts, ceramics, metalwork and human remains, to Yale for study, under an agreement with the Peruvian government intended at the time to be temporary.
A century-long return
Peru spent decades pressing Yale to return the collection. A 2007 agreement began the process, and after further negotiation and a 2011 lawsuit threat from Peru, Yale agreed to return the roughly forty thousand pieces in its holdings, with objects transferred in stages through 2012, now housed in Cusco's Casa Concha museum.
Managing the crowd Bingham started
Machu Picchu's popularity, driven substantially by Bingham's own 1911 and 1912 National Geographic coverage, has since forced Peru to impose timed entry tickets, fixed circuit routes and daily visitor caps to limit erosion and damage to structures never built to carry modern tourist volume.