Amazon explorers uncover signs of a real El Dorado
Rory Carroll
Condensed by Native Village

It's the legend that drew explorers and adventurers to their deaths: an ancient empire of citadels and treasure hidden deep in the Amazon jungle.

Spanish conquistadors spent centuries looking for it.  Other followed. Some called it El Dorado, others the City of Z. All were convinced they would find a lost civilization to rival the Aztecs and Incas.

But the jungle swallowed the legend, and nothing was found. The world called El Dorado a myth.

The world was wrong.

New satellite and aerial pictures reveal more than 200 huge geometric earthworks carved in the Amazon near Brazil's border with Bolivia. The shapes span 155 miles and form a network of avenues, ditches and enclosures.  They date between 200 - 1283 AD.

Scientists say another 2,000 structures may exist beneath the jungle canopy. They were made by a "sophisticated pre-Columbian monument-building society," says the journal, Antiquity.

The structures were created by a network of trenches about 36 feet wide, several feet deep and banked up to 3 feet high.  Some are ringed by low mounds containing ceramics, charcoal and stone tools.

Many mounds were symmetrical and slanted north, perhaps for astronomical reasons.

These Amazon engineering feats are being compared to the skill of building ancient Egypt's pyramids.

Researchers were also surprised that the floodplain and upland earthworks were of a similar style. This suggests both were built by the same culture.

"In Amazonian archaeology you always have this idea that you find different peoples in different ecosystems," said Denise Schaan, anthropologist at the Federal University of Pará in Brazil. "So it was odd to have a culture that would take advantage of different ecosystems and expand over such a large region."

The discoveries also prove that upper Amazon soils could support extensive agriculture, Schaan said.

It is thought the area maintained a population of 60,000 – more than many large European cities.

In the Xingu region, interconnected villages known as "garden cities" have also been discovered.  Dating between 800 - 1600, they included houses, moats and palisades.

"These revelations are exploding our perceptions of what the Americas really looked liked before the arrival of Christopher Columbus," said David Grann, author of The Lost City of Z.  "The discoveries are challenging long-held assumptions about the Amazon as a ... place where only small primitive tribes could ever have existed, and about the limits the environment placed on the rise of early civilizations."