A 1500-year-old Amazonian city, full of artificial lakes, large public plazas, and agricultural regions (including fish farms), is being excavated and mapped for the first time in modern memory. Until recently, the remains of the ancient city had been almost completely hidden by jungle. A group of Brazilian and U.S. researchers report in tomorrow's issue of Science that they used satellite photos to determine that the now-vanished city was structured as a group of small towns connected by roads, ditches, and shared farmlands. The researchers say the lifestyle here was clearly "urbanism," and compared it to cities that one might have seen in Ancient Greece or medieval Europe. The city was located in a region of the Amazon known as Upper Xingu (today in Brazil), which is currently inhabited by people of the Kuikoro tribe. Members of the Kuikoro helped identify the remains of the towns to scientists. In this satellite photo (below), the red lines are raised berms that would have served to elevate roads and plazas, while black lines show ditches that were used for defensive purposes.

Scientists have found about 28 ancient town sites in the region, each of which they estimate probably contained about 800-1000 in the "inner city" area, and about 1500 more in outlying farm areas. So each town probably had about 2500 people, making the region really quite dense and populous. According to MSNBC:

Each village had a central plaza, the team reports. Larger communities could cover 150 acres (60 hectares) and included gates and secondary plazas. And each settlement had a formal road connected to the central plaza and oriented northeast to southwest, the direction of the summer solstice . . . . [Anthropology professor Mike] Heckenberger and his colleagues said the findings suggest future solutions for supporting the modern-day indigenous populations in Brazil's state of Mato Grosso and other regions of the Amazon - and demonstrate that the area can return to a "pristine" state even after centuries of human activity. "Some of the practices that these folks hammered out may provide alternative forms of understanding how to do low-level sustainable development today," Heckenberg said.

No one knows for sure what happened to the city, but one of the more common theories is that its population was wiped out by diseases brought by European colonists about 500 years ago. How the Amazon's Cities Worked [MSNBC]