Machu Picchu, one of the most visited archaeological sites on the planet, is a 15th-century Inca site perched high on a mountainside in Peru. In 1911, the late Hiram Bingham III, a Yale University professor, rediscovered the site. Until then, the ancient ruins had escaped the notice of Spanish conquistadors and settlers. Many archaeologists believe Machu Picchu was once the royal estate of Pachacuti Inca Yupanqui, an Inca ruler from the 14th century.