
A huge ancient city has been found in the Amazon, hidden for thousands of years by thick vegetation.
Historians say this discovery changes what we know about the history of people living in the Amazon.
The houses and plazas in the Upano area of ??eastern Ecuador were connected by an amazing network of roads and canals.
The area lies in the shadow of a volcano that created rich lands for the locals, but may also have led to the destruction of society.
While only cities in the highlands of South America were known, such as Machu Picchu in Peru, it was believed that people lived only nomadically or in small settlements in the Amazon.
“This is older than any other site we know of in the Amazon. We have a Eurocentric view of civilization, but this shows that we need to change our idea of ??what culture and civilization are," said Prof Stephen Rostain, director of the investigation at the Center for Scientific Research in France, which led the research.
"This changes the way we see Amazonian cultures. Most of the people appear in small groups, perhaps naked, living in huts and scavenging the land - this shows that ancient people lived in complex urban societies," said co-author Antoine Dorison.
The city was built about 2,500 years ago and people lived there for up to 1,000 years, according to archaeologists.
It is difficult to estimate exactly how many people lived there at any one time, but scientists say it is between 10,000, if not 100,000.
The archaeologists combined the ground excavation with a survey of an area of ??300 square kilometers using laser sensors from an aircraft that could identify the remains of the city under dense plants and trees.
This LiDAR technology found 6,000 rectangular platforms measuring about 20 m by 10 m and 2-3 m high.
They were arranged in groups of three to six units around a square with a central platform.
Scientists believe that many of them were houses, but some were for ceremonial purposes. One complex, at Kilamope, included a platform 140 m by 40 m.
They were built by cutting into hills and creating a platform of earth on top.