A massive Maya city was found in Mexico — here’s how its builders made it last

The city, discovered by chance in Mexico’s southeastern state of Campeche, has been named Valeriana after a nearby lagoon. Archaeologists uncovered pyramids, ballcourts, causeways linking different areas, and amphitheaters. Valeriana appears to rank just behind Calakmul—the largest Maya settlement—in population density.

The complex was revealed in Mexico’s dense jungle using LiDAR, a geospatial technology that fires laser pulses to detect hidden features and build three-dimensional maps of the terrain.

The Fortunate Find of a Graduate Archaeologist

Luke Old-Thomas, a graduate student at Tulane University, stumbled on traces of the city while sifting through unexamined LiDAR data he’d found online.

“I was somewhere around the 16th page of a Google search when I found a laser survey conducted by a Mexican environmental monitoring organization,” he explained. But when Old-Thomas processed the LiDAR data with archaeological techniques, he saw what others had missed: a vast ancient city that, at its peak (between 750 and 850 A.D.), could have housed between 30,000 and 50,000 residents.

Professor Marcello Canuto, a co-author of the study, says the discovery helps reshape Western views that the tropics were places where “civilizations perished.” In reality, this region hosted advanced, complex cultures.

The team found that Valeriana shows “capital city” features and is second only to Calakmul—about 100 kilometers away—in urban density. Archaeologists think locals may have suspected ancient ruins beneath the earth mounds.

The city, covering approximately 16.6 square kilometers, featured two major centers with large buildings situated two kilometers apart, connected by dense construction and causeways. The team discovered two plazas with temple pyramids where the Maya worshipped their gods, stored treasures such as jade masks, and buried their dead. There was also a court where they likely played ball games. The team also found signs of a reservoir at Valeriana.

Overall, Old-Thomas’s team surveyed three jungle sites and identified 6,764 buildings of various sizes, the BBC reports.

The study confirmed that the collapse of the Classic Maya civilization, beginning around 800 A.D., was partly due to overpopulation in cities that could not withstand climatic stresses. The Spanish conquest in the 16th century further contributed to the destruction of the Maya city-states.

The findings were published in the journal Antiquity.

What’s the Secret to the Resilience of Ancient Maya Cities?

Old-Thomas noted, “You can see columns along the facades of public buildings. They are in very good condition.”

So what’s the secret? How did Maya architecture survive? Recent studies point to building techniques that strengthened mortar and plaster — including the addition of natural rubber, organic binders, and volcanic ash.

Juan Carlos Fernandez-Diaz, an engineer at the University of Houston who has mapped Mesoamerica with LiDAR for 15 years, says Maya architecture has survived remarkably well.

One reason is that the Maya built in stone, which doesn’t rot like wood. They also made a special mortar that kept stone structures from collapsing into piles of rubble, the BBC reports.

Builders mixed natural materials — blood, eggs, and natural rubber tapped from local trees — into their mortar. Analysis of mortar from the main pyramid at Witzin revealed saturated fats typical of natural rubber. Maya masons used that rubber, with fine clay, as a binder to create a strong mortar that held the stone masonry together.

Another team studying mortar samples from Rio Bec in southeastern Campeche found evidence that the Maya added volcanic ash to strengthen the mix.

Archaeologists have long known that the Maya were skilled at making lime plaster, which they used to coat floors and walls, bind stones, and decorate surfaces.

They discovered the plaster’s durability came from additives: the juice of chukum and chiote tree bark boosted strength, while extracts from guasuma trees acted as a fixative, preserving painted layers.

Those organic additives also helped stop the material from washing away in heavy tropical rains and hurricanes.

Other studies point to another reason the ruins have endured: dense vegetation made the sites hard to access, which shielded them from development and looting.