Drone Uncovers Hidden Mega-Fortress in the Caucasus Mountains

The study of urbanization and ancient social dynamics is enriched by an exceptional discovery: a 3,000-year-old fortress, located in the south of the Caucasus, revealed by drone aerial mapping techniques. Led by Nathaniel Erb-Satullo, of Cranfield University, and Dimitri Jachvliani, of the Georgian National Museum, this research published in the journal Antiquity highlights Dmanisis Gora, a strategic site at the crossroads of Europe, Asia and the Middle East.

Revolutionary cartography: the drone

Initially perceived as a small fortification, the true scale of Dmanisis Gora was revealed thanks to drones. The researchers deployed a DJI Phantom 4 RTK. This drone equipped with high precision sensors allows a relative positioning accuracy of less than 2 centimeters. This device captured 11,000 high-resolution aerial images, used to generate orthophotos and digital elevation models (DEMs). Orthophotos are georeferenced and distortion-corrected aerial images, providing a complete orthogonal view of a terrain. They have thus revealed fortifications, residential structures, tombs and agricultural systems formerly invisible from the ground. Using these images, researchers mapped a site 40 times larger than initially estimated. They found a main fortification stretching over a kilometer.

Map of the Dmanisi plateau and surrounding areas. © R. Higham and N. Erb-Satullo

To contextualize this data, the researchers compared recent orthophotos with satellite images from the Cold War period, declassified in 2013. These old photographs were integrated into a geographic information system (GIS). This allowed a chronological and spatial analysis of landscape transformations over several decades. The researchers were thus able to distinguish intact historical elements from alterations caused by modern agriculture. By combining these different data sources, the team identified seasonal variations in occupation and changes in land use. In addition, they provided unprecedented details on the dynamics of settlement and exploitation of the site through the ages.

A monumental architecture impossible to grasp from the ground

The fortresses of the South Caucasus appeared between 1500 and 500 BC. They represent an unprecedented development in the prehistory of these regions. Situated on the border between Europe, the Eurasian steppe and the Middle East, the Caucasus region has a long history as a cultural crossroads with distinct local identities.

Map of Dmanisis Gora highlighting archaeological features. The red dotted line indicates the extent of drone photogrammetry. © N. Erb-Satullo

Research on the fortress began with exploratory excavations on the promontory between the two deep gorges. A subsequent visit in autumn, when the knee-high summer grasses had disappeared, revealed that the site was much larger than originally thought. The remains of additional fortification walls and other stone structures were scattered over a large area outside the inner fortress.

Due to its size, it was impossible to get a sense of the entire site from the ground. “ This gave rise to the idea of ​​using a drone to assess the site from the air. “, commented Dr. Erb-Satullo.

A mega fortress in the Caucasus seen by drone

The monumental remains of Dmanisis Gora therefore reveal an imposing fortress. And strategically perched between two gorges more than 60 meters deep. The heart of the site includes a 1.5 hectare fortified structure. It is surrounded by cyclopean walls reaching a thickness of 2 to 2.5 meters. They are built without mortar with carefully arranged stone blocks. These walls, supplemented by natural gorges, create an exceptional defensive perimeter. Beyond this core, a second enclosure, one kilometer long, protects a vast exterior area of ​​80 hectares. It is home to residential structures, circular tombs and agricultural remains. The fortifications indicate an advanced design, exploiting natural reliefs to maximize their effectiveness and ensure the safety of the inhabitants.

The excavations have in fact highlighted a multifunctional use of the site. The wall segments suggest low density occupation, potentially linked to seasonal uses. Ceramic fragments and animal bones confirm a sophisticated agro-pastoral economy. The stone tombs scattered throughout the outer enclosure reveal a ritual dimension. The rectilinear and curvilinear structures seem to have accommodated both dwellings and spaces for herds. They thus reinforce the hypothesis of cohabitation between sedentary people and nomads. This architectural ensemble testifies to a complex social organization. The fortress served as a strategic assembly point and refuge. This fortified city reflects a balance between mobility and sedentary lifestyle in the societies of the Caucasus of the Bronze Age.

A window into the Eurasian past

Dmanisis Gora offers a unique perspective on how ancient societies in the Caucasus maintained remarkable cultural stability in times marked by upheaval elsewhere. Unlike the social collapses observed in the Middle East and the Eastern Mediterranean around the 12th century BC. BC, the discoveries show that the Caucasus continued a trajectory of continuity. “ Archaeological data reveals a persistence of agricultural, pastoral and architectural practices in this region », underlines Nathaniel Erb-Satullo. Circular stone tombs, local ceramics and defensive structures indicate a society that was able to withstand environmental pressures and conflict. It relied perfectly on a combination of local strategies and regional interaction networks.

The site also highlights the complexity of settlement patterns in this region of Eurasia. According to Dimitri Jachvliani, these temporary pastoral migrations fostered vital economic and cultural exchanges, consolidating a flexible and resilient social system.

The authors conclude: “ We hypothesize that Dmanisis Gora expanded due to its interactions with mobile pastoral groups. Its large outdoor establishment was able to expand and contract seasonally “.

They also point out that the site is now widely mapped. Further studies will then begin to provide information on areas such as population density and intensity, livestock movements and agricultural practices, among others.

Source: Erb-Satullo NL, Jachvliani D, Higham R, Weber-Boer KO, Symons A, Portes R. “Mega-fortresses in the South Caucasus: new data from southern Georgia”. Antiquity. Published online 2025:1-20. doi:10.15184/aqy.2024.197