A new Mayan city, lost in the dense jungle of southern Mexico for centuries, has been discovered from the computer of a PhD student hundreds of miles away. This is the story of how he did it.

The settlement, named Valeriana after a nearby freshwater lagoon, has all the characteristics of a classic Maya political capital: enclosed plazas, pyramids, a ball court, a reservoir, and an architectural layout that suggests a foundation prior to 150 AD, according to a newly published study in the journal Antiquity.

And how did Tulane University graduate student Luke Auld-Thomas find it? The answer lies in lasers. Until recently, archaeology was limited to what a researcher could observe from the ground and with their eyes. However, the technology of detecting and measuring distances with light, known as lidar, has revolutionized the field, allowing us to scan entire regions in search of archaeological sites hidden under dense vegetation or concrete.

Let’s travel back in time. It is 1848 and the governor of Petén, Guatemala, Modesto Méndez, together with Ambrosio Tut, an artist and chronicler of the time, rediscovered Tikal, one of the most majestic archaeological sites of the Mayan civilization. In the middle of the 19th century, little was known about this advanced culture—which calculated lunar, solar, and Venusian cycles, and invented hieroglyphic writing and the concept of the number zero with hardly any tools.

The dense rainforest surrounding Tikal and its lack of roads made it extremely difficult to reach the remains. But the Guatemalan government went deep into the heart of the Petén jungle anyway, in search of its cultural heritage. Guided by the rumors of the locals, machete in hand, along with tape measure and compass, they entered the Petén jungle on an almost impossible mission. Arriving at the Tikal site, Méndez and his team were amazed at what they saw: gigantic temples and pyramids, mostly covered by the jungle. The most imposing constructions, hidden by nature, towered above the tree canopy. Tikal, although partially buried, retained its majesty and gave clues to the enormous size of the city.

History repeated itself in 2024—but with some important variations. Rather than a machete, Auld-Thomas armed himself with a search engine. WIRED spoke this week with him and Marcello Canuto, director of Tulane’s Middle American Research Institute, about the discovery.

Anna Lagos: How did you come across Valeriana by accident? What initially caught your attention in the lidar data?

Luke Auld-Thomas: It was both deliberate and accidental. The mapping project was undertaken in 2013 by a group of ecologists who were mapping the distribution of above-ground frest biomass in Mexico. So they basically wanted to say how much carbon is in Mexico’s forests and how it is distributed. Lidar is very good at mapping trees in addition to mapping ground. And so they undertook a really large survey throughout Mexico and published their data in 2014 and then made the data available and it just kind of sat there. Nobody was seeming to do very much with it. It was on the digital equivalent of a high, dusty shelf: out of sight and out of mind.

I read some research published by some colleagues working in Mexico that had analyzed another data set collected by NASA, also focused on environmental science questions. They’ve looked at it for archeological purposes and said hey, this seems like a really interesting sample from a methodological standpoint. And I thought, well that’s kind of cool. I wonder if there’s more of this kind of thing out there.

So I just started poking around on the internet and eventually got the right combination of search terms and number of Google pages results in and found this data set. As soon as I opened it up I was delighted, surprised, and amazed that the area they had mapped with absolutely no interest in finding archaeological sites at all was really archaeologically important. And one of their survey blocks which was intended to map trees had actually mapped trees growing on top of a really large Maya city that was previously unknown to the scientific community. And it’s like a 15 minute walk off the highway.

Could you explain how these lidar data sets were repurposed for archaeology?

Auld-Thomas: The main difference between the way that ecologists use lidar and the way that archaeologists use it is that ecologists are interested in everything that’s happening above ground level. For archaeologists, it’s the inverse. The first thing we do is digitally select and delete all of the vegetation to look at the ground in an archaeological context, which usually involves ruined buildings that have fallen over and become mounded through time.

We enlisted a colleague at the University of Houston who specializes in collecting and processing lidar data for archaeologists, and had him use his algorithms that have been tuned over a period of more than a decade for squeezing out every last bit of terrain detail.

These algorithms are based on slope thresholds, where you set a threshold for what is likely to be a natural slope and what’s likely to be artificial, like the edge of a building. Because Maya architecture in this part of the world is so well-preserved and the buildings are so steep, the original out-of-the-box ground-detecting algorithm had sheared off the tops of all the buildings assuming that they were buildings. That was one reason reprocessing this data proved really valuable: It allowed us to capture all of the architectural detail that was otherwise so well-preserved that the scan was ignoring it.

Is it surprising to you that such a large city has not been discovered before? Why do you think it remained hidden for so long?

Auld-Thomas: It was very surprising. I think it goes to show that cities like this are not actually rare in the Maya region; large dense cities with monumental architecture and lots of residential buildings all around them are commonplace.

I wanted to ask you also about the impact of climate change on the disappearance of Valeriana. What role do you think climate change played in the collapse of the Maya cities?

Marcello Canuto: Generally speaking, the archaeological community agrees that climate change played a role in the collapse of Maya civilization in the Classic Lowlands. However, it was not a total disappearance. The Maya culture survived, and today many people continue to speak Mayan languages and practice their traditions. What happened was a political and demographic collapse, not a cultural one.

Auld-Thomas: Yes, and the interesting thing is that densely populated cities, like Valeriana, were more exposed to climate change. When the whole landscape is full of settlements, there is less flexibility for people to move to new areas in times of drought or crisis. Densely populated societies are more vulnerable to these changes.

How do you see the balance between development and preservation of archaeological heritage in the region?

Canuto: There will always be debates about how to balance development and conservation of cultural heritage. In Mexico, the law states that cultural heritage belongs to the people, and it is INAH’s responsibility to manage and preserve it. Having more detailed archaeological data definitely helps to have a more informed discussion about how and where to develop.

Auld-Thomas: It’s a discussion that every country should have, about how to manage their cultural legacy and enable development. For us, as foreign archaeologists, we always follow the laws of the country and respect the decisions of the local authorities.

Do you have plans to visit Valerian soon?

Auld-Thomas: Yes. Although my current work is more focused on remote sensing and not so much on field excavations, I’m excited about what we’ll discover when we visit Valeriana in person.

Canuto: That’s right. We are in talks to visit the site with the INAH team to see up close what the lidar has revealed. Although we have not yet fully defined our next steps, I think the potential for further research in this area is enormous.

With so many technological advances such as lidar and artificial intelligence, how do you see the future of archaeology? What are your prospects for future discoveries?

Auld-Thomas: I hope this research inspires archaeologists around the world to start working with found or repurposed data sets that have been collected and are sitting around gathering dust. I think the Maya world is the tip of the iceberg in that sense, and there’s a lot more to be found globally.

The other thing I’ll add is that sensor development is happening really rapidly, and the quality of lidar data is improving, as is the scale at which it can be collected efficiently. I think it’s only a short matter of time before new kinds of sensors are able to map much larger areas very quickly. We’re rapidly approaching the era where these small windows we’ve been afforded by available technology are going to be blown open like the Kool-Aid man crashing through them.

Canuto: Yes, and another important aspect is access to digital data. I think in the long term this should be an open science exercise. The only reason we were able to do this study was because somebody decided to make this data available. You also have to think about the risks, such as misuse of the data, but science advances when researchers have access to the information and can analyze it from different perspectives. In Mexico, for example, INAH has made a lot of lidar data available to the public, which has led to incredible discoveries.

Auld-Thomas: I remember 20 years ago, I was reading a story about an Egyptologist who looked in Google Earth and found a sight. I remember thinking to myself, “Oh, lucky Egyptologists, they can just look at Google Earth and discover archaeological sites.” In the Maya region, we’ll never be able to do that because there are so many trees everywhere. But with lidar, that is changing. We are starting to have the ability to analyze large areas, share that data and allow other researchers to study it. These maps are there for everyone to look at.

This story originally appeared on WIRED en Español and has been translated from Spanish.