Archaeologists have uncovered a massive lost Mayan city, named Valeriana, hidden under the jungle in Campeche, Mexico. Using Lidar technology, which detects structures beneath vegetation, they discovered pyramids, plazas, and causeways, revealing a city as large as Edinburgh and likely home to 30,000-50,000 people around 750-850 AD. Found by chance through an online radar survey, Valeriana rivals other major Mayan sites like Calakmul. The city includes ancient game courts, temples, and reservoirs, showing the Mayans’ complex urban life. Climate change, overpopulation, and later Spanish conquest likely contributed to its decline.