From ground level, you wouldn’t realize what you’re standing on. But laser data gathered by archaeologists reveals a stunningly large monument.

The monument measures nearly 4,600 feet in length (1,400 meters), is up to 50 feet (15 meters) high, and includes nine wide causeways.

The Mexican state of Tabasco, close to the border with Guatemala, is known for its cuisine, culture, and archaeology. Much of that is owed to the Maya and Olmec civilizations that inhabited the area centuries ago.

But archaeologists had no idea that such a huge monument was hiding beneath the surface. The fact that it was so huge only worked to hide it even better.

Oftentimes, buried or half-buried archaeological features aren’t visible to the naked eye, but they can easily reveal their secrets to lidar — or light detection and ranging — technology. Laser beams are sent from a plane or drone, penetrating the forest canopy and revealing the surface features on the ground in three-dimensional form. It is exactly this approach that revealed the sprawling Mayan monument.

University of Arizona professors in the School of Anthropology Takeshi Inomata and Daniela Triadan noticed something was off when they looked at lidar data from the Mexican government, but couldn’t really assess what they were dealing with. So they went and carried a more detailed lidar survey.

“Using low-resolution lidar collected by the Mexican government, we noticed this huge platform. Then we did high-resolution lidar and confirmed the presence of a big building,” Inomata said. “This area is developed—it’s not the jungle; people live there—but this site was not known because it is so flat and huge. It just looks like a natural landscape. But with lidar, it pops up as a very well-planned shape.”

The immense Mayan platform is a remarkable find in itself, but it also has significance for the overall history of the Maya civilization. It was thought that the early Mayans only lived in small villages up until about 350 BC, but this new monument might force us to rethink that timeline.

The team excavated the site and radiocarbon-dated 69 samples of charcoal to determine that it was constructed sometime between 1,000 to 800 BC, which makes this not only the largest Mayan monument ever found — but also the oldest.

The monument is also similar to those produced by the older Olmec civilization center of San Lorenzo to the west in the Mexican state of Veracruz. This seems to add more weight to the idea that the two civilizations are somehow related, researchers say.

“There has always been debate over whether Olmec civilization led to the development of the Maya civilization or if the Maya developed independently,” Inomata said. “So, our study focuses on a key area between the two.”

Large ancient structures aren’t necessarily just for pharaohs

It’s not fully clear why the role of the monument was. The period in which this was built marked a gap in power — after the decline of the Olmec San Lorenzo complex, and before the rise of another one. It was a period when different cultural ideas were exchanged in the area, and the monument seems to feature multiple cultural influences. This, along with its sheer size, suggests that it was meant to be used by many people. It is very likely ceremonial in purpose, but the researchers stop short of speculating.

It’s also noteworthy that the monument appeared in a period when there was less inequality in Mayan society. These large-scale monuments typically appear in stratified ancient societies, such as that of the Egyptians, for instance. This changes the assumption that it’s only that type of society that can produce monuments, spurring archaeologists to rethink the construction process.

“It’s not just hierarchical social organization with the elite that makes monuments like this possible,” Inomata said. “This kind of understanding gives us important implications about human capability, and the potential of human groups. You may not necessarily need a well-organized government to carry out these kinds of huge projects. People can work together to achieve amazing results.”

“During later periods, there were powerful rulers and administrative systems in which the people were ordered to do the work. But this site is much earlier, and we don’t see the evidence of the presence of powerful elites. We think that it’s more the result of communal work,” he said.