MEXICO CITY — A huge Mayan city has been discovered centuries after it disappeared under a jungle canopy in Mexico. Archaeologists found pyramids, sports fields, causeways connecting districts and amphitheaters in the southeastern state of Campeche. They found the hidden complex — which they have called Valeriana — using Lidar, a type of radar survey that maps structures buried under vegetation.

They believe it is second in size only to Calakmul, thought to be the largest Mayan site in ancient Latin America. The discovery of the city, which is the size of Scotland's capital Edinburgh, was made “by accident” when one archaeologist browsed data on the internet. “I was on something like page 16 of Google search and found a radar survey done by a Mexican organization for environmental monitoring,” explains Luke Auld-Thomas, a PhD student at Tulane University in the US.

It was a Lidar survey, a remote sensing technique that fires thousands of radar pulses from a plane and maps objects below using the time the signal takes to return. But when Auld-Thomas processed the data with methods used by archaeologists, he saw what others had missed — a huge ancient city which may have been home to 30-50,000 people at its peak from 750 to 850 AD. That is more than the number of people who live in the region today, the researchers say.

Auld-Thomas and his colleagues named the city Valeriana after a nearby lagoon. The find helps change an idea in Western thinking that the Tropic.