Recently, new satellite imagery detected a hidden kingdom in the Amazon that had eluded explorers for nearly 500 years.
Some called it El Dorado, others, like Colonel Percy Harrison Fawcett (a British version of Indiana Jones) cryptically named it the "City of Z."
The jungle swallowed them all, and no evidence has ever been produced that such a place existed.
Now the satellite imagery of deforested sections of the upper Amazon Basin revealed more than 200 geometric earthworks.
Sculpted from the clay rich soils of Amazonia as perfect circles and squares, these structured earth mounds, or "geoglyphs," are located on the east side of the Andes and span a distance of 155 miles.
Built long before Christopher Columbus set foot in the new world - the sites date from 200 to 1283 A.D.– the earthworks are the remains of roads, bridges and squares that formed the basis for a lost civilization, according to a study published in the journal Antiquity.
Denise Schaan, co-author of the study and anthropologist at the Federal University of Pará, in Belém, Brazil, tells Discovery News about this intriguing finding.
According to Schaan and colleagues Martti Parssinen from the University of Helsinki and Alceu Ranzi from the Federal University of Acre, Rio Branco, Brazil, the structures are formed by ditches about 36 feet wide and several feet deep, lined by earthen banks up to 3 feet high.
But who built the structures and what functions they had remains unclear.
Schaan and colleagues estimated at least 300 people would be needed to build a geoglyph. This points to a regional population of around 60,000 people, which was then wiped out by diseases brought by European conquistadores in the 15th and 16th centuries.
The researchers believe that the sites already found make up only 10 percent of what is actually there.