Machu Picchu is a special place with a tangled history. The one thing that we know for sure is that the Incas built it at the height of their empire in the 15th century. The other thing we know is that following the rapacious onslaught by the Spanish conquistadors, the site was abandoned in the 16th century and largely forgotten, as the surrounding forest claimed the grand ruins.

We still don&rsquot know for sure what it had been built for, maybe as a royal settlement, maybe a city, maybe a religious establishment, or maybe even as a crop-testing centre The photo here was taken in 1912 by the American explorer and adventurer Hiram Bingham. A faculty member at Yale University, he was travelling through Peru in 1911 searching for Inca ruins when a local farmer led him to the site, and Bingham realised that he had struck gold. He returned the next year under the auspices of the Royal Geographical Society, cleared the site and started excavations. In 1913 the National Geographic dedicated its entire issue to Machu Picchu and Bingham went on to write the bestseller The Lost City of the Incas and a wonder of the world was born.