Built at the height of the Incan civilization in what is now Peru, Machu Picchu was rediscovered on 24 July, 1911, by Yale University scholar Hiram Bingham. (Eitan Abramovich/AFP/Getty Images/Life.com)
Three Peruvian locals stand on a masonry ledge of Machu Picchu and look out over a deep valley at one of the Amazon's source streams in 1911. (Frederic Lewis/Getty Images/Life.com)
Machu Picchu features ingenious engineering designs for an area prone to earthquakes. (Eitan Abramovich/AFP/Getty Images/Life.com)
The site was designed to be impenetrable by invaders, defended at its back by a nearly insurmountable mountain and protected by steeply terraced walls. (Eitan Abramovich/AFP/Getty Images/Life.com)
(Medioimages/Photodisc/Life.com)
Remarkably, Machu Picchu was never found and plundered by the Spanish explorers despite the fact that it was close to the Incan capital, Cusco. (Dennis Hallinan/Life.com)
Machu Picchu was abandoned about 100 years after it was founded, possibly because of a smallpox epidemic. Scholars still debate over the site’s intended use. (Eitan Abramovich/AFP/Getty Images/Life.com)
(Eitan Abramovich/AFP/Getty Images/Life.com)
