Now, that very city, and the rainforest that surrounds it, is under siege by deforestation, wildlife trafficking, illegal land-grabbing, and the looting of treasured artefacts.
Many of these crimes are tied up with the process of illegal cattle ranching, which involves cutting back trees to make room for cattle to graze. Around 90% of deforestation in the Moskitia rainforest is attributable to illegal livestock.
That's a problem not only for the vaunted White City, but for the safety of the entire planet. As the second-largest rainforest in Central America, the Moskitia is a critical tool for absorbing greenhouse gas emissions, which contribute to climate change. It's also a refuge for endangered or threatened wildlife species like the spider monkey and jaguar.
In November, the Honduran government launched an initiative to end local deforestation by removing all livestock and evicting cattle ranchers from the rainforest. The government will also endeavour to reclaim the land, which is in danger of being cut in half in less than five years.
The mission represents a critical effort to preserve a once-forgotten territory, allowing researchers to dig deeper into its storied past.
More than half a millennium after the collapse of the Mayan civilisation, the members of a neighbouring Central American society suddenly gathered their most sacred belongings, buried them in the centre of town, and vanished.
"There's a big question about who these people were," the best-selling author Douglas Preston, who visited the remnants of the city, told Business Insider. "What happened to this civilisation? Why did they abandon this city so suddenly?"
Preston was part of a research mission launched three years ago to explore the ruins of this lost civilisation. He wrote about his trip through the Honduran jungle in the book, "The Lost City of the Monkey God: A True Story."
Some have said that the buried remnants correspond with an ancient, legendary "White City" - a town of extreme wealth that disappeared some 600 years ago. Since the 1900s, rumours of this forgotten city had danced on the lips of explorers, aviators, and tourists excited by the prospect of uncovering hidden treasure. But no one knew much about the people who once lived there.
Even after some parts of an abandoned village, including remnants of plazas and pyramids, were uncovered in 2012, during the first expedition to the area, anthropologists and archaeologists remained stumped.
"In the words of the leading Honduran archaeologist on our expedition, 'What we know about this culture is ... nothing,'" said Preston.
Nevertheless, some intriguing theories have emerged. Researchers on the most recent trip found a cache of nearly 500 intricately carved stone objects inside something Preston described as "a grave not for a person, but for a civilisation."
The 1,000-year-old ruins - whose timeline coincides with the "White City" - were buried in the rainforest, in a round valley ringed by steep cliffs. Since a team of researchers uncovered them in 2012, they've been revisited by more research teams, including Preston's.
When news outlets picked up the story, most portrayed it as an ancient mystery that had finally been solved. National Geographic ran with the headline "Exclusive: Lost City Discovered in the Honduran Rain Forest." NPR announced "Explorers Discover Ancient Lost City in Honduran Jungle."
There was one problem, though, according to researchers who signed a public letter condemning the claims in the news: The ruins were not the "lost city" of lore - and worse, they may not have been lost to begin with.
The dissenting researchers - including Chris Begley, an archaeologist at Transylvania University who has 20 years of experience in the region - said the National Geographic story exaggerated the findings and ignored the region's indigenous people. National Geographic responded to the letter by linking to a statement from the research team that says its story never claimed to have discovered the "lost city," but merely a lost city in the region.
Controversy notwithstanding, the teams of researchers and documentarians who visited the site in 2012 and 2015 came away riveted by what they'd seen. Preston and several other archaeologists maintain that they set foot on terrain that had been untouched for half a millennium. And they say the clues these people left behind point to a tragic end.
"It's hard to believe that in the 21st century a lost city could still be discovered, but that's exactly what happened," he said. "People hadn't touched foot there in 500 years. It's absolutely true."
Whoever populated the area deep in Honduras' Moskitia Jungle did not leave many clues. The team that visited in 2012 was able to date the remains it uncovered to somewhere between 1000 AD and 1400 AD. That places people in the region after the era of the Mayans, whose civilisation stretched from southeastern Mexico across Guatemala and Belize and into the western portions of Honduras and El Salvador.
"They grew up near the Mayans. They took on the pyramids. They laid out their cities in a somewhat Mayan fashion, but not quite," Preston said. "But it's very mysterious. There's so much we don't know."
What researchers do know is that whoever lived there disappeared suddenly. In addition to rough remnants of their pyramids and plazas, they left behind a series of intricate stone pieces, including what is thought to be part of a ceremonial seat featuring an effigy of a "were-jaguar." So far, researchers have identified nearly 500 of the stone pieces.
"At the base of a pyramid we discovered an enormous cache of beautiful stone sculptures," Preston said. "It appears the people brought their objects, carefully laid them to rest, and then walked out of the city."
Several archaeologists and anthropologists who were on Preston's research team believe the people were felled by disease.
"The evidence is very strong that that's what happened," Preston said. "These were diseases brought by Europeans, specifically smallpox and measles."
But it's unlikely that Europeans ever reached this civilisation - at least not in person. Instead, the diseases probably found the indigenous populations by way of trade. As goods exchanged hands, so did viruses. And some of these invaders were foreign illnesses against which the indigenous people had no defence.
"This is a fascinating example of how disease can run way ahead of physical contact," Preston said. "Even though this valley was never physically threatened by the Spanish, it may have been laid low and completely wiped out by their disease."
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