In January, author Douglas Preston released his latest book, The Lost City of the Monkey God: A True Story. In 2015, Preston had been part of an expedition to Honduras that located an unexplored city deep in the rain forests of the country, one that belonged to an as-of-yet unknown civilization.

The book deals with the history of efforts to explore the legendary “White City,” and more recent efforts from archeologists to track down its location. The site had first been located in 2012 when archeologists used Light Detection and Ranging (LIDAR) surveys to explore the dense jungle. The system works by using lasers to calculate distances: it’s been used in everything self-driving cars to astronauts mapping the Moon. In recent years, archeologists have begun using the technology to survey archeological sites from planes, often discovering structures that can’t be seen from the ground.

When Preston accompanied a team of archeologists to explore the city on foot, they found an undisturbed set of ruins overrun by the forest, likely untouched since it was abandoned. The cities belonged to a previously unknown civilization, and the reasons for its collapse aren’t known, although Preston speculates that the apocalyptic pandemics could have played a role.

The site was not without dangers: the city is located in a region controlled by drug cartels, while deadly snakes and forest creatures roam the jungle. The peril continued even after they departed: the team discovered that while on site, they had been infected by a flesh-eating parasite.

We spoke with Douglas Preston about the city and the research that he has recounted in his book.

This interview has been edited and condensed for clarity.

Your book, The Lost City of the Monkey God is about a long-lost Honduran civilization that was recently discovered. Are there other places around the world that might be out there, hidden?

There are certainly more lost cities hidden in the heavily jungled mountains of Mosquitia. As the book shows, our LIDAR survey turned up not one but two lost cities, and the second one — as large as the core of Copan — has not been explored at all.

While doing aerial reconnaissance of Mosquitia, back in 2012, our expedition team spied gigantic sinkholes and monumental cave openings in an exceedingly remote area of rugged karst topography east of the Patuca River, near the Nicaraguan border. The only way to get into this area would be by rappelling down from a hovering chopper. Clearly an extensive cavern system lies in this area, and our research indicates it has never been entered or explored in modern times. Because the ancient inhabitants of the region buried their dead in caves, these caverns likely hide major necropolises, ossuaries, and other archaeological treasures. It has been alleged that during the Contra war people were thrown out of helicopters into these gaping sinkholes, so there may be more awaiting the explorer than prehistoric burials.

Other scientifically unexplored areas where there might be undiscovered ruins include the deeper parts of the Amazon and the heavily forested mountains in the central highlands of Peru. Finally, most of the sea bed has never been explored and there are many shipwrecks and natural wonders to be found.

You use the first part of the book to explore some of the history of the region and how this city has been seeped in local legend. It's fascinating how impenetrable this part of the world is. How much did geography and terrain help shield the ruins?

Geography — natural and human — has everything to do with why the city remained undiscovered. In this area, some of the thickest rain forest on Earth covers precipitous mountain chains, some over a mile high, with roaring torrents, frequent landslides, steep ravines, waterfalls, pools of quick mud that will swallow a person alive, and noxious insects carrying diseases. The understory is infested with deadly snakes, jaguars, and thickets of catclaw vines with hooked thorns that tear at flesh and clothing. In Mosquitia, an experienced group of explorers, well equipped with machetes and saws, can expect to journey two to three miles in a brutal 10-hour day. The towns and rural areas surrounding the jungle are largely controlled by drug cartels, with a murder rate that is the highest in the world. The fierce physical terrain, combined with surrounding lawlessness and violence, have protected this area for centuries.

I wonder how pulp stories like Indiana Jones feed into this. I know some archeologists cringe at the name. 

Archaeologists cringe for good reason. Until recently, many archaeologists were shockingly insensitive and arrogant in the way they conducted fieldwork, riding roughshod over the feelings, religious beliefs, and traditions of indigenous people. They dug up burials without permission, put human remains and sensitive grave goods on public display in museums, hauled off sacred objects to which they had no legal right of ownership. Today the profession has reacted against this dark history and tried to make fundamental changes in the way they conduct fieldwork and work with local people.

I might add that the expedition chronicled in my book had 12 PhD scientists on it, including three top archaeologists. While the spectacular discovery of a lost city and the “curse” that afflicted the expedition has a crazy Indiana Jones flavor to it, this was a serious and careful scientific expedition.

A major component of the exploration here was LIDAR. You talk a bit about how it's been used to uncover other ruins around the world: how do you see its use in transforming our understanding of the past?

LIDAR is a truly revolutionary technology. One archaeologist said it was the greatest breakthrough since Carbon 14 dating.

To give one example: in one week of surveying the Maya city of Caracol with LIDAR, archaeologists uncovered tens of thousands of archaeological features that had not been found in 25 years of intensive ground surveys. The first LIDAR survey of the Mexican site of Angamuco uncovered 20,000 previously undiscovered features, including entire pyramids missed by the ground surveys! Mark my words: when the Amazon Basin and the highlands of Peru are surveyed with LIDAR, we can expect spectacular, incredible, and mind-boggling discoveries to be made. LIDAR will open up the rain forest like a book, which we can then read with ease.

The LIDAR machine we used cost about a million dollars, but even if the price of the machine goes down, the expense of flying the specially modified plane will not. Some of the hardware in the LIDAR box is classified, and we had to hire armed soldiers to guard our plane 24/7 while it was on the ground, which was an additional expense. Just getting in and out of these remote areas by aircraft is pricey and dangerous.

Do you think there will be resistance to this technology in academic archeology?

As might be expected with any disruptive technology, some of the old guard has resisted and even condemned it. Rosemary Joyce, a distinguished archaeologist at UC Berkeley, wrote that “LIDAR can produce images of landscapes faster than people walking the same area, and with more detail. But that is not good archaeology, because all it produces is a discovery—not knowledge… [LIDAR] may be good science—but it is bad archaeology.”

On the other hand, younger archaeologists are all over LIDAR. They absolutely love it. One young archaeologist, who was using LIDAR to map Native American sites in Maine, told me: “LIDAR is crack!”

Let's talk about the city that you guys discovered. After finding it with LIDAR, you had to ground truth it. What was it like standing in a place that you know (or believe) hasn't been visited for centuries?

I can recall the very moment when we stumbled over the cache of sculptures at the base of an earthen pyramid. I first saw a carved jaguar head coming out of the ground. Gleaming with rain, it rose up snarling, as if struggling to escape the earth. It was an image that spoke directly to me across the centuries — forging an immediate, emotional connection to these vanished people. What had been theoretical for me became real: this spirited image had been created by people who were confident, accomplished, and formidable. Standing in the gloom among the ancient mounds, enveloped in the mist, I could almost feel the presence of the invisible dead.

How well preserved is this city?

The stone artifacts are beautifully preserved. The great temples and public buildings of this lost civilization, however, were built out of adobe, beautifully polished tropical hardwoods, and draped with spectacular textiles — all perishable materials. Their buildings and cities may well have been just as magnificent as the cut-stone temples of the Maya. But once abandoned, they dissolved in the rain and rotted away, leaving behind unimpressive mounds of dirt and rubble that were swallowed by vegetation. In the acidic rain forest soils, no organic remains survive — not even the bones of the dead. So in that sense it is not well preserved. However, the city was pristine and unlooted, which is exceedingly rare for any site in Central America.

What types of artifacts have been recovered from the site, and what do they tell us about the civilization?

The most spectacular discovery was the cache of sculptures found at the base of a pyramid. In a broad hollow area, just poking out of the ground, we came across the tops of dozens of extraordinary carved stone sculptures — 52 in all. The objects, glimpsed among leaves and vines, and carpeted with moss, took shape in the forest twilight: the jaguar head mentioned above, great stone jars carved with vultures, snakes and monkeys, objects that looked like thrones or tables, many with carvings along the rims and legs. These sculptures were in beautiful condition and had probably been lying undisturbed since they had been left centuries ago — until we stumbled across them.

Excavation of the cache revealed it was vast: over 500 sculptures and fragments, with many more still buried as of this writing. They had all been left at the same time when the city was abandoned, many ritually broken to release their spirits, a common practice for objects placed in a grave. But this cache was not the grave of a person — it was the grave of the entire city. Archaeologists theorize that a mysterious a catastrophe struck the city, killing most of the inhabitants. The survivors gathered up all their sacred objects, placed them as an offering to their gods, and walked away — never to return. My book explores the cataclysm that destroyed the city and, in fact, shattered the entire civilization.

What progress has been made in research on the site now that a year has passed since you were last there?

The excavations are temporarily suspended, but the site is still being guarded by soldiers. The city is vast; over a mile square. Only about 40 square meters have been excavated down to a depth of only 18 inches. There is a lot more work to be done, if it is done at all. (There are excellent arguments for not excavating the rest of the city.) Either way, research on the site will go on for many years, if not centuries.

While you were there, you and several other researchers were infected with Leishmaniasis, a disease caused by protozoan parasites.

Mucosal leishmaniasis struck down two-thirds of the expedition — Hondurans, Americans and Brits alike. It is a very persistent disease, a flesh-eating parasite that attacks the face and eventually causes your lips and nose to slough off, leaving a weeping sore where your face used to be. (I would not recommend Googling pictures of the disease!) It has returned in a number of people. But we are getting the best medical care in the world from doctors at the National Institutes of Health, who are studying us and our disease, which appears to be a unique form. It makes for a fascinating medical mystery.

You're the brother of Richard Preston, who famously wrote The Hot Zone and several other books. What was his take on this disease? You spend some time at the end of the book examining the disease and how it's becoming more prevalent. 

My brother and I both have an interest in exotic and gruesome diseases. (As children we were often sent away from the dinner for telling disgusting stories.) Richard was shocked and concerned when he learned I had the disease. He’s writing another book about Ebola and had to be quarantined for three weeks after returning from a research trip to Sierra Leone, during the Ebola outbreak, but thank God he’s never gotten that disease. It is, of course, much worse than leish.

Would you go back?

Yes, without hesitation. It is a remarkable and breathtaking wilderness, unlike any other place I’ve seen. I’ve already got leish so I can’t get it again! Of course, there are other diseases, not to mention the snakes, but nothing truly worth accomplishing is without risk.

Why do you think we're so attracted to these sorts of legends and myths about lost or hidden places around the world?

It is incredible to think that a lost city could still be found in the 21st century, but that is precisely what happened. People feel the world has shrunk. We have trodden upon, mapped, photographed, and exploited every place on Earth to the point where it feels like we’ve robbed the world of its mystery. But this discovery puts some of that mystery back. It proves we don’t know everything, and it shows us there are still places on Earth that are indifferent, hostile, or even inimical, to human beings. Mosquitia is one such place.