A massive Maya landscape has been hiding under a forested area of southern Mexico.

The newfound city, dubbed Valeriana, spans an area roughly the size of Beijing and has “all the hallmarks of a Classic Maya political capital,” researchers report in the October Antiquity. Its plazas connected by a large passageway, temple pyramids and water reservoir might have impressed Mayans over 1,500 years ago.

Archaeologists have long known that the Maya Lowlands, in the southernmost region of Mexico, harbors ancient urban settings (SN: 10/25/21). When archaeologist Luke Auld-Thomas, of Tulane University in New Orleans, was looking at random data online, he saw a dataset that Nature Conservancy Mexico (TNC Mexico) was using to study carbon intake and emissions in that region. He saw that the organization was looking into a place with high archaeological potential and had a hunch there could be structures there.

Further analysis showed the hunch was right. Auld-Thomas “hit the bullseye while blindfolded,” says Tulane anthropologist Marcello Canuto. “We weren’t expecting to find such a big site with such a small dataset.”

TNC Mexico’s environmental analysis had used a technology called lidar to estimate tree heights and canopy volumes in the southern tip of Mexico. With lidar, researchers use laser beams from aircraft to map undulations in a landscape. It has been used to uncover many archaeological sites such as high-altitude Silk Road cities, a massive ancient urban complex in Ecuador and long-forgotten urban sprawl in the Amazon (SN: 10/23/24; SN: 1/11/24; SN: 5/25/22).

While lidar beams that reached the forest ground were of little use to TNC Mexico’s focus on tree coverage, they provided good data for Auld-Thomas and his colleagues to create a topographic map for archaeological purposes.

Reprocessing that data showed that Valeriana, nestled in the much larger Lowlands subdivision of the Maya region, could have been quite densely settled. Inhabitants living in the many houses surrounded by curved, amphitheater-like residential patios may have enjoyed their time in the nearby lagoon, the researchers speculate, or at the city’s ball court, if they were not at the pyramidal temples taking part in rituals.

With over 400 structures per square kilometer, Valeriana had, at its peak, a building density more than seven times that of most of the surrounding region. Only the massive Lowlands city of Calakmul, near the current Mexico-Guatemala border, was historically denser, at about 770 buildings per square kilometer.

“It’s great to put numbers to the suspicions we had that this might be one of the most densely populated zones of the ancient Maya in the area,” says David Stuart, an anthropologist at the University of Texas at Austin who was not involved in the new study.

The finding is not just about a site no one knew about before, Stuart says. “It’s about the nature of how the Maya settled on their landscape.”

Driving around that region, he says, it is possible to see mounds and pyramids shaping the landscape of the now agricultural fields, and “ancient agricultural terraces [that were] a breadbasket of agricultural activity in ancient times.” The study adds more evidence that the Maya Lowlands were, indeed, densely populated beyond just Calakmul, which thrived during the Maya Classic period (250-900 AD) and could have had a population of over 50,000. “And the fact we found this out with environmental data shows that previous archeological research suggesting this density was not an overestimation,” Stuart says.

Archaeologist Thomas Garrison, also at the University of Texas, agrees. He considers lidar technology to be helping his field make large strides. “This study showcases the value that lidar data can have to archaeology even when it is acquired for other purposes,” he says. Lidar data from regions that are not extensively known help archaeologists get a clearer, inarguable image of the pieces in the Maya civilization puzzle. But lidar data is not all. “The next step would be to visit and excavate these settlements to gain a better understanding of them.”