“We were able to identify the layout of the streets of this city, which was also a fascinating discovery,” Eduardo Neves, director of the University of São Paulo’s Museum of Archaeology and Ethnography, said in a statement that captures the understated excitement of science encountering serendipity. Under the thick, uncompromising green of the Amazon rainforest, a forgotten 18th-century Portuguese colonial city has risen from centuries of obscurity, its presence attested not by serendipitous excavation, but by the piercing eye of airborne LIDAR and the lived experience of local communities.
The Amazon’s dense canopy has long foiled explorers and archaeologists alike. For years, the idea of huge, structured settlements under its canopies was ridiculed as myth, a remnant of conquistador imagination. Yet as Neves’s team from the Amazônia Revelada project showed, reality often exceeds the imagination and is richer than rumor. Their research, carried out in the Brazilian state of Rondônia, employed LIDAR (Light Detection and Ranging) to virtually remove the canopy of the forest, revealing a city that had disappeared from view and memory after independence in Brazil in the early 19th century.
LIDAR works by emitting bursts of rapid pulses of laser light from aircraft, recording the time taken for each pulse to return from the ground. This creates a thick “point cloud,” which, when processed, results in a high-resolution 3D map of the terrain even when it is hidden under coverings of vegetation. In Rondônia, this technology uncovered a forgotten street grid and geometric terrain features squares, circles, and line traces that could have defined roads, fields, or ceremonial areas under the forest. We still don’t know exactly what they are. They could be areas of cultivation or perhaps places of habitation, but we will have to go back to the field to excavate and better understand their meaning, Neves told Metrópoles.
It is not the first time that LIDAR has overturned conventional wisdom about Amazonian history. In Bolivia, comparable surveys have revealed urban sites with monumental platforms, causeways, and water management, transforming our vision of pre-Columbian Amazonia as a mosaic of advanced, dense societies and not as pristine wilderness recorded by remote sensing. The Brazilian find is distinctive in its colonial context. The city, founded by Portuguese colonizers and fueled by the toil of enslaved Africans, was a centre of resource extraction sugar, gold, coffee before being forgotten and covered by both time and the forest’s inexorable march forward.
That technological leap is only half the narrative. The Amazônia Revelada project stands out for its engagement with Indigenous and traditional communities, whose understanding of the land is as profound as the forest’s roots. These local researchers, frequently descendants from rubber tappers and beiradeiros, contribute to field surveys, document places of cultural importance, and assist in the interpretation of outcomes that technology cannot explain independently through collective mapping. “We want to register these archaeological sites to make them part of [our] heritage and create an additional layer of protection for these territories,” Neves reinforced in a press release.
The project’s dual strategy bringing advanced remote sensing together with local involvement mirrors a wider change of direction in archaeological practice. The combination of machine learning and Geographic Information Systems (GIS) is now complementing LIDAR data analysis. Pattern-recognition algorithms that have been trained on point clouds are able to pick out faint traces of ancient canals, field boundaries, and settlement plans, even in landscapes that have been severely modified by past machine-based activity, under machine learning with LiDAR. However, as recent research warns, the tools work best in conjunction with skilled interpretation and ground-truthing, as natural features can be readily confused with man-made ones.
The 3D reconstructions created using LIDAR and GIS more than show us lost cities; they enable scientists to simulate how colonial towns engaged with their landscape. The recently discovered city of Rondônia, for instance, has a grid of streets and geometric form consistent with both European town planning and Indigenous land use, and it indicates a complicated overlaying of cultures and technologies. These virtual models also aid conservation, offering accurate maps that can guide legal protection and sustainable management of archaeological sites.
Such finds defy the enduring fantasy of the Amazon as a barren, primeval wasteland. As Neves has put it, When the first scientists began traveling through the Amazon in the eighteenth century, they found the region empty, and its ancient settlements covered by forests. The absence of stone structures contributed to the false idea that took hold over time: the Amazon was empty. The new evidence now piling up from LIDAR, soil sampling, and oral traditions paints a different picture of a landscape sculpted by centuries of human creativity, adaptation, and perseverance.
The stakes are more than mere academic interest. The Brazilian law safeguards Amazonian archaeological sites, and their records provide an additional vital layer of protection against deforestation and land appropriation. The work of the project, funded by the Brazilian Socio-Environmental Institute and its overseas partners, is one as much concerned with the future as the past: charting the unseen foundations of Amazonian society to protect both rainforest and cultural heritage alike.
For archaeology and history enthusiasts, the fusion of LIDAR, machine learning, and community knowledge in the Amazon is a vivid demonstration of how technology and tradition can work hand in hand. Each new survey flight, each point cloud rendered, and each story shared by local custodians brings us closer to understanding not just what was lost, but what endures beneath the trees.
