A US PhD student has accidentally uncovered a sprawling ancient Maya city hidden beneath dense jungle in Campeche, Mexico. While browsing data online, Luke Auld-Thomas from Tulane University found a laser survey by a Mexican environmental agency. When he processed the Lidar data using archaeological techniques, he discovered a lost city with an estimated population of 30,000 to 50,000 at its peak between 750 and 850 AD. Named Valeriana after a nearby lagoon, the site spans 6.4 square miles and includes temple pyramids, plazas, sports courts, and a reservoir, all linked by intricate causeways. Lidar, which uses laser pulses to reveal structures buried under vegetation, has transformed archaeology in the region, revealing complex civilizations where few expected them. Valeriana, said to rival the famous Calakmul site, challenges the Western idea that tropical landscapes could not support advanced societies. "The landscape was completely settled," remarks Professor Elizabeth Graham, noting that densely populated cities like Valeriana may have collapsed due to climate pressures. Although more Maya sites are being uncovered, the sheer number exceeds archaeologists’ capacity to excavate them all. “It’s close to a major road, but we may never fully explore it,” says Auld-Thomas, highlighting both the excitement and challenge of modern archaeological discovery.