Imagine discovering a lost city while you are pulling an all-nighter to finish your history paper. That’s what happened to an archeology student studying in Tulane University in Louisiana. Luke Auld-Thomas, a doctoral student at Tulane spotted the ancient Mayan site in the scans collected by NASA using lidar, a technology that uses airborne lasers to penetrate dense vegetation. The ruins were unknown to archaeologists, but some farmers living in that region of Mexico were aware of the site‘s existence. Luke and his colleagues named the lost city Valeriana, after a nearby lagoon. They estimated the city may have had a population of as many as 50,000 people at its peak between AD 750-850. Researchers expect to discover more ancient Mayan cities in the future. The findings will make the collapse of Mayan civilization even more mysterious: The more people there were, the more difficult it is to explain the massive depopulation later on.