The year was 1531. A Spanish conquistador called Juan Martinez lay on his deathbed. With the final breath in his body, he confessed a secret: the story of a long lost place, deep in South America. It was an isolated city he stumbled across when lost in the jungle, a place safe from the ravages of the European conquerors. The people there were kind and peaceful, and astonishingly wealthy. For they lived in a great city of gold, on the edge of a giant lake whose shores were laced with gold dust. The Spanish called it El Dorado, and it has become legend. Does recent evidence suggest it really existed? El Dorado has captured the imagination of the world ever since the first rumours of its existence emerged in the early 16th century. At least 20 expeditions have gone in search of it. So certain were explorers that it was real, numerous early maps of South America include the lost city.

Juan Martinez, the catalyst for the craze, claimed he found the city after becoming separated from an expedition led by Diego de Ordaz. De Ordaz was already looking for El Dorado along the Orinoco River, but never found it. Martinez, however, got lost floating downriver on a canoe. Carried by the current, he was eventually found by a native tribe who blindfolded him and took him to their emperor, Inga. They were kind to him – Emperor Inga treated him like a royal guest, feeding him and housing him in his great palace, where everything was made of gold. The native Indian empires were incredibly rich in gold – the Spanish seized or mined most of it during their conquest. For instance, Francisco Pizarro ransomed the Inca ruler Atahualpa for 24 tonnes of gold and silver.

Estimates suggest up to 180 tonnes of gold and 16,000 tonnes of silver were brought from the New World to the Old. The precise amount is unknown, because most of it was melted down and traded around the world. Martinez did not call the city El Dorado. He called it Manoa, and said the journey to it from the Orinoco lasted fourteen or fifteen days. He claimed he lived there