A hundred years ago in Peru, a tall history professor from Yale University left his camp in a valley northwest of Cusco, and walked through cloud forest to a mountain ridge more than 7,500 feet above sea level. There, high above the roaring Urubamba river, he found an ancient stone citadel; sculpted terraces of temples and tombs, granite buildings and polished walls that were covered in centuries of vines and vegetation.

Hiram Bingham had stumbled across the Inca site of Machu Picchu, the site he believed to be the ‘Lost city of the Incas’. ‘Machu Picchu might prove to be the largest and most important ruin discovered in South America since the days of the Spanish conquest,’ he wrote in the 1913 edition of the National Geographic.

But his words were misleading. Bingham hadn’t ‘discovered’ Machu Picchu.  Nor was it ‘lost’. He may have alerted it to the western scientific world – for there were no accounts of it in the chronicles of the Spanish invaders – but local tribes must have been aware of its existence. Yet Christopher Heaney, a Fellow at the University of Texas and author of a book on Hiram Bingham, claims the historian was amazed to discover an indigenous family close to the citadel. ‘When he climbed the mountain he was very surprised to find an Indian family at the top of the ridge,’ he said.  Why Bingham was surprised is bewildering in itself....