Machu Picchu: Inca roads and terraces uncovered by lidar in Peru

A discovery made possible by lidar

According to Archaeology magazine, which draws on a report by Science in Poland, the structures were detected by lidar scanning from a drone. Lidar is a remote sensing technique that fires laser pulses at the ground: once the vegetation canopy is digitally filtered out, it reveals the terrain and the features buried beneath the plants.

This method is especially valuable in mountain tropical forests, where dense vegetation makes foot surveys long and difficult. It helps direct fieldwork toward the most promising areas, avoiding random trekking across impassable slopes.

Checking on the ground, machete in hand

Once the images had been analysed, the researchers returned to the site to verify the structures. Heavy vegetation had to be cleared with machetes, a task that illustrates the difficulty of surveying steep forested terrain.

Among the paths observed, one less than a metre wide was already known to local residents. Bartłomiej Ćmielewski, of the University of Science and Technology in Wrocław, is part of the team, alongside Mariusz Ziółkowski of the University of Warsaw. This collaboration between Peruvian and Polish researchers combines local knowledge with recent survey tools.

Features to date and interpret

The layout of the routes is consistent with Inca construction techniques, which dominated the Andes until the arrival of the Spanish in the 16th century. Mariusz Ziółkowski notes, however, that these alignments could predate the Inca period, since Andean societies occupied these slopes long before the empire.

The researchers believe there are "certainly at least twice as many" structures still to be found, suggesting that the area surrounding the citadel was far more developed than assumed. Without precise dating, the chronological attribution remains open for now.

What the discovery changes for Machu Picchu

The discovery indicates that the surroundings of Machu Picchu, a UNESCO World Heritage Site, were far more developed than current knowledge suggested. The roads, terraces and platforms point to a organisation of the territory, of movement, and of agricultural or ritual activities linked to the citadel.

Inca terraces, called andenes, were used to farm steep slopes by retaining soil and limiting erosion. The features recorded near Machu Picchu fit this logic of mastering the relief and attest to remarkable agricultural and technical know-how.

Next research and further reading

The team plans to continue lidar surveys across the whole region surrounding the citadel. These upcoming campaigns should help place the features more precisely in time and clarify their links with the main site.

Readers interested can refer to the article "Inca Workers' Homelands", published by Archaeology in its list of the ten greatest discoveries of 2023, which also covers recent research at Machu Picchu. Inca sites in Peru can also be visited in museums and archaeological parks in the Cusco region.