Elevated fortified settlements are among the most distinctive archaeological features of the western Balkans. Their distribution extends from the eastern Adriatic coast to the mountainous interior of Bosnia and Herzegovina, Montenegro, Albania, and adjacent regions. Although these settlements differ in size, chronology, and architectural complexity, many occupy remarkably similar topographic settings. Mountain ridges, isolated plateaus, and naturally protected summits were repeatedly selected for permanent occupation. Such regularity suggests that the relationship between human communities and the landscape followed recognizable patterns rather than isolated local decisions ([30]; [5]; [17]).

Landscape has long been understood as more than a physical setting for human activity. It shapes movement, communication, territorial organization, and social identity while simultaneously being modified through human occupation and construction ([16]; [1]; [2]; [18]). Elevated places offered practical advantages, including extensive visibility, natural protection, and access to construction material, but they could also acquire symbolic significance through their prominence within the surrounding environment. The repeated selection of similar locations throughout prehistory indicates that environmental, strategic, and cultural considerations often operated together rather than independently ([28]; [31]).

Within this broader landscape, fortified settlements conventionally attributed to Iron Age Illyrian communities represent one of the defining archaeological characteristics of the western Balkans. Monumental dry-stone walls preserved at Daorson, Varvaria, Asseria, Meteon, and numerous other sites demonstrate considerable technical knowledge, organized labour, and long-term planning ([34]; [29]; [8]; [4]). At the same time, ‘Illyrian’ is itself a label with a complex historiography: it derives largely from external, later Greek and Roman ethnography rather than from an attested Iron Age self-designation, and its retrospective application to specific material-culture groups has been increasingly questioned in recent scholarship ([11]). Regional chronological syntheses further show that Bosnian hillfort communities were organized into multiple, only partly related archaeological groups (e.g., the Glasinac and Central Bosnian groups) whose settlement histories, internal chronologies, and degree of shared ethnic identity remain actively debated rather than settled ([14]). This paper therefore uses “Illyrian” as a conventional archaeological label for a recognized regional Iron Age fortification tradition, not as an assertion about the ethnic identity of Kolun’s builders. Such achievements point to socially organized communities capable of mobilizing resources for large-scale construction projects and adapting complex mountain environments to their needs. While chronology and regional development continue to be discussed, the engineering and spatial organization of these settlements leave little doubt that their builders possessed sophisticated knowledge of construction, landscape, and defensive planning. Comparable evidence for the deliberate selection of elevated, naturally defensible terrain has been documented at other eastern Adriatic hillforts, including Grad on the Pelješac peninsula and the wider Dalmatian gradina tradition ([12]; [22]; [6]).

Previous investigations of Illyrian hillforts have focused primarily on architecture, excavation results, chronology, and material culture. Comparatively less attention has been given to why particular mountain summits were selected for settlement and how natural landforms influenced the organization of fortified landscapes. Modern geospatial technologies have significantly improved archaeological documentation during the past two decades, allowing researchers to examine settlement morphology, visibility, terrain, and spatial relationships with unprecedented precision ([9]; [13]). These methods provide an opportunity to reconsider fortified settlements not simply as isolated defensive structures, but as carefully selected components of a broader cultural landscape.

The Kolun Hillfort, situated near the village of Mrežica in southeastern Bosnia and Herzegovina, occupies a limestone plateau reaching approximately 1190 m above sea level, with elevations across the fortified enclosure itself ranging from 1158 to 1191 m a.s.l. and the wider surveyed extent spanning 1082 - 1248 m a.s.l. (Figure 1; §3.1, Table 1). Despite its imposing position and well-preserved dry-stone fortifications, the site has remained virtually uninvestigated. Prior to the present research, no systematic archaeological documentation, geodetic survey, airborne LiDAR acquisition, UAV photogrammetry, or GIS analysis had been undertaken. The integrated documentation presented here, together with the companion geospatial-methods paper ([25]), establishes the first comprehensive spatial record of the site and creates a permanent reference framework for future archaeological, anthropological, architectural, and environmental investigations. As with any fortified site known only from surface observation, the Illyrian Iron Age attribution used throughout this paper is provisional: it follows typological comparison with regional hillforts rather than excavated stratigraphy or absolute dating, and probable later reuse (e.g., during the Middle Ages) cannot be excluded (see §2.7, Limitations).

Figure 1.Location of the Kolun Hillfort within the southeastern Dinaric Alps of Bosnia and Herzegovina. Situated at an elevation of approximately 1190 m above sea level, the site occupies a naturally prominent mountain summit overlooking the surrounding landscape.

Several questions arise from the position and organization of the Kolun Hillfort. Why was this particular summit selected when numerous surrounding elevations were available? Which natural characteristics contributed to its defensive potential? To what extent did the builders adapt their enclosure to the morphology of the plateau? Does the pronounced north–south orientation of the summit influence the alignment of the defensive walls? Finally, how does Kolun compare with other Illyrian fortified settlements distributed across the western Balkans?

Particular attention is given to the relationship between natural landforms and human construction. The elongated north–south orientation of the summit plateau is reflected in the alignment of the principal defensive walls, suggesting that the builders deliberately adapted the settlement to the mountain’s existing morphology rather than reshaping it extensively. This relationship between natural topography and architectural organization has received little attention in studies of Illyrian hillforts and forms one of the central themes of the present analysis. The regional distribution of Illyrian territories during the Late Iron Age (Figure 2) situates Kolun within this broader cultural landscape and its long-recognized network of highland communities occupying naturally defensible terrain.

Figure 2.Approximate distribution of Illyrian territories during the Late Iron Age, showing the location of the Kolun Hillfort within the mountainous cultural landscape of the western Balkans.

The investigation combines archaeological field observations with high-resolution geospatial documentation and comparative anthropological analysis. The objective was not to establish chronology through excavation or artifact analysis, but to examine how the physical characteristics of the landscape influenced the selection and organization of the settlement. The methodological framework therefore integrates direct observation of preserved architectural remains with quantitative spatial documentation and regional comparison.

The Kolun Hillfort is interpreted here as demonstrating that the selection of elevated settlements during the Iron Age involved considerably more than the search for defensible terrain. The physical characteristics of the site reveal a close relationship between natural topography and human decision-making, indicating that environmental, strategic, economic, and symbolic considerations collectively influenced settlement planning. Rather than treating the mountain as an obstacle to be modified, the builders incorporated its existing morphology into the organization of the settlement, thereby maximizing the advantages already provided by the landscape.

One of the most significant observations concerns the relationship between the natural north-south orientation of the summit plateau and the alignment of the principal defensive walls. The enclosure closely follows the elongated ridge instead of imposing an independent geometric plan upon it. This adaptive approach plausibly reduced the need for extensive earthworks, minimized the volume of stone required for construction, and preserved the natural defensive strength of the mountain. The resulting settlement represents a balance between human engineering and environmental adaptation rather than complete transformation of the landscape.

This principle of architectural adaptation has broader anthropological implications. Throughout prehistory, communities repeatedly selected locations where natural landforms could be incorporated into settlement planning with relatively limited modification ([30]; [5]; [16]; [2]). Kolun provides a particularly clear example of this relationship because the ridge’s morphology remains directly reflected in the preserved layout of the enclosure. The builders appear to have recognized that the mountain itself constituted an essential component of the defensive system, requiring reinforcement only where natural protection was comparatively weak.

The geological characteristics of the site also appear to have contributed to settlement organization. Extensive limestone outcrops supplied abundant building material immediately adjacent to the occupied area while simultaneously forming steep escarpments that functioned as natural barriers. This combination plausibly reduced construction effort and created a defensive system in which natural and built elements became structurally inseparable. Similar integration of bedrock and dry-stone architecture has been documented at several major Illyrian hillforts throughout the western Balkans, although the degree of preservation varies considerably from site to site ([34]; [29]; [4]). Comparable dry-stone construction techniques have also been documented in other archaeological contexts in Bosnia and Herzegovina, including the subterranean river-pebble dry-stone walls of the Ravne Tunnel Complex ([24]). Comparable dry-stone traditions, analyzed with similar remote-sensing methods, have recently been documented on the Adriatic island of Cres and at the hillfort of Grad on the Pelješac peninsula, reinforcing the regional character of this construction technique ([10]; [12]).

Visibility represents another important component of landscape selection. From the summit, field observation and orthophoto/DEM inspection indicate extensive views extend across surrounding valleys, mountain passes, and neighboring ridges. Such visual dominance plausibly enhanced defensive awareness, but it may also have reinforced territorial identity and social presence within the broader cultural landscape. Elevated settlements frequently occupy positions that are not only strategically advantageous but also visually prominent, suggesting that practical and symbolic considerations often developed together rather than independently ([1]; [18]; [2]). Comparable relationships between visibility, territorial control, and symbolic prominence have been discussed for prehistoric hillfort landscapes of the eastern Adriatic more broadly, where elevated hillfort sites recur as markers of territory and communication across the Bronze and Iron Ages ([6]; [15]).

The present investigation also demonstrates the value of integrating modern geospatial technologies with anthropological interpretation. UAV photogrammetry, RTK-GNSS surveying, airborne LiDAR, and GIS analysis provided the first comprehensive spatial documentation of the Kolun Hillfort, allowing subtle relationships between terrain morphology, architecture, and settlement organization to be examined quantitatively ([7]; [33]; [21]; [23]). These technologies do not replace archaeological interpretation; rather, they provide objective spatial evidence that strengthens anthropological analysis and establishes a permanent reference framework for future investigations. The approach is consistent with, and extends, the author’s earlier geospatial studies of the Ravne tunnel system and the wider Bosnian Valley of the Pyramids, which applied comparable LiDAR- and GIS-based methods to different classes of site ([26]).

Because Kolun had not previously been subjected to systematic archaeological or geospatial documentation, the present study represents the first comprehensive scientific record of the site. The datasets generated during this investigation provide an essential baseline for future excavation, conservation, environmental monitoring, and comparative studies of Illyrian fortified settlements. Equally important, they demonstrate how non-invasive documentation can substantially expand archaeological knowledge even in the absence of large-scale excavation.

Although this investigation focuses on a single hillfort, its implications extend beyond Kolun itself. The recurring association between elevated topography, natural defensive features, local building materials, ridge morphology, and settlement organization suggests that similar principles may have influenced the selection of numerous hillforts across the western Balkans conventionally grouped under the ‘Illyrian’ label. The Kolun Model of Illyrian Landscape Selection, proposed in §3.6, offers one way of organizing these recurring associations into a testable framework; future comparative investigations employing standardized geospatial documentation and the explicit comparison variables of §2.3 may determine whether they constitute a broader regional pattern of settlement planning.

Rather than interpreting hillforts solely as military installations, the evidence from Kolun supports a more comprehensive anthropological perspective, consistent with broader conceptions of settlements as constructed and inhabited cultural landscapes ([2]; [31]). The settlement is interpreted as reflecting deliberate interaction between human communities and the mountain environment, in which defence, resource availability, landscape morphology, visibility, and social organization may have been integrated into a coherent system of occupation. Understanding these relationships contributes not only to the archaeology of communities conventionally described as Illyrian but also to broader discussions of how prehistoric societies selected, organized, and transformed prominent landscapes.

The present investigation is based primarily on non-invasive archaeological documentation and anthropological interpretation of the preserved landscape. Although the integrated use of UAV photogrammetry, RTK-GNSS surveying, airborne LiDAR, and GIS analysis provides an exceptionally detailed spatial record of the Kolun Hillfort, questions concerning chronology, construction phases, duration of occupation, cultural attribution, and internal settlement organization can only be resolved through systematic archaeological excavation and laboratory analyses.

Four points define the immediate research agenda arising from this study. First, the ‘Illyrian’ attribution (with probable later reuse) remains provisional pending excavated stratigraphy and absolute dating (§1, §4.4). Second, systematic quantitative extraction of wall lengths, orientations, plateau area, slope ranges, and the accessible-versus-naturally-protected perimeter from the existing vectorized survey dataset (§3.1, Table 1; [25]) is planned as a dedicated follow-up geospatial analysis. Third, a formal viewshed analysis on the existing 0.3 m LiDAR-derived DEM—with observer height, viewing radius, vegetation treatment, and corridor-identification criteria specified in advance—is planned to place the visibility observations in §3 and §4 on a quantitative footing (§2.2). Fourth, field-measured application of the §2.3 comparison variables at Daorson, Varvaria, Asseria, and Meteon would allow the Kolun Model to be tested quantitatively across sites rather than only illustratively.

Nevertheless, the absence of previous scientific investigations makes the present study an essential foundation for future research. The geospatial datasets generated during this project establish a permanent reference framework against which future archaeological discoveries can be accurately documented and interpreted.

Future investigations should combine excavation, geophysical prospection, archaeobotanical and zooarchaeological analyses, radiocarbon dating, micromorphology, and expanded landscape studies to reconstruct the settlement’s occupational history more comprehensively. Comparative application of identical documentation methods at other Illyrian hillforts throughout Bosnia and Herzegovina and the western Balkans would also permit quantitative evaluation of whether the landscape-selection principles identified at Kolun—and formalized in the Kolun Model proposed in §3.6—represent a broader regional pattern.

The Kolun Hillfort is presented here as a candidate example of how communities conventionally labeled Illyrian may have selected and organized elevated sites within the mountainous terrain of the western Balkans, an attribution that remains provisional pending excavation (§1, §4.4, §5). Rather than relying solely on artificial fortifications, the builders appear to have incorporated the natural characteristics of the limestone plateau into the overall organization of the occupied enclosure, integrating topography, geology, visibility, and locally available construction materials into a coherent defensive and residential whole.

One of the principal findings of this investigation is the close correspondence between the morphology of the summit ridge and the alignment of the principal enclosure walls. The settlement follows the natural north–south orientation of the plateau (≈1190 m a.s.l.; §3.1) instead of imposing an independent architectural geometry upon the landscape. This relationship is interpreted as demonstrating that the builders adapted their construction to existing landforms, maximizing natural defensive advantages while minimizing unnecessary modification of the terrain. The observed integration of natural and built features represents one of the defining characteristics of the Kolun Hillfort and contributes to a broader understanding of prehistoric settlement planning.

The study also presents the first comprehensive scientific documentation of the Kolun Hillfort. Prior to this investigation, the site had not been systematically surveyed or analyzed using modern geospatial technologies. The integration of UAV photogrammetry, RTK-GNSS surveying, airborne LiDAR, digital elevation modelling, and GIS analysis has produced the first high-resolution spatial record of the settlement, establishing an important reference framework for future archaeological, anthropological, conservation, and environmental research.

Beyond documenting a previously uninvestigated archaeological site, the research proposes an anthropological model—the Kolun Model of Illyrian Landscape Selection—for understanding hillfort location and organization, offered explicitly as a testable hypothesis. The evidence indicates that landscape selection may have been influenced by the combined interaction of topographic prominence, natural protection, availability of building materials, accessibility, visibility, and adaptation to ridge morphology. These factors should not be viewed as isolated variables but as interconnected components of a hypothesized settlement strategy, summarized in Table 2.

Although based on a single case study, the findings have broader implications for the investigation of Illyrian fortified settlements throughout the western Balkans. Similar analyses conducted at other hillforts may determine whether adaptation to natural landscape morphology represents a recurring principle of settlement planning within this regional tradition. Such comparative research would contribute not only to regional archaeology but also to wider anthropological discussions concerning the relationships between human communities, architecture, and mountain landscapes.

The Kolun Hillfort is proposed as demonstrating that successful prehistoric settlements may have been shaped through collaboration between human ingenuity and the natural environment. Rather than transforming the mountain into an artificial fortress, its builders appear to have integrated architecture with the existing landscape, creating a settlement in which natural and constructed elements functioned as a unified system. This perspective expands our understanding of Illyrian hillforts beyond their defensive role and highlights the importance of landscape adaptation as a fundamental aspect of prehistoric community organization.

The author expresses sincere gratitude to GeoGIS Studio d.o.o., Sarajevo, for conducting the comprehensive geodetic survey, UAV photogrammetry, airborne LiDAR acquisition, and spatial data processing that formed the foundation of this investigation. Special appreciation is extended to Mr. Alija Žutić and his professional team for their technical expertise, precision, and commitment throughout the field documentation and data analysis.

The author also acknowledges the support of colleagues and collaborators who assisted during the field investigations and provided valuable discussions regarding the archaeological and anthropological interpretation of the Kolun Hillfort.

The geospatial datasets generated and analyzed during the present study, including UAV photogrammetry, RTK-GNSS measurements, digital elevation models, GIS datasets, and airborne LiDAR-derived products, are retained by the author. Selected data supporting the findings of this study are included within the article. Additional materials may be made available by the corresponding author upon reasonable request.

The author used ChatGPT (OpenAI, GPT-5.5) during the preparation of the original manuscript, and solely as a language-editing and drafting assistant to improve the organization, clarity, and readability of the text and to assist in developing the manuscript structure. The AI tool was not used to generate original scientific data, perform analyses, interpret archaeological evidence, produce figures, or draw scientific conclusions. All archaeological observations, interpretations, references, figures, and final editorial decisions were independently verified by the author, who assumes full responsibility for the accuracy, originality, and integrity of the manuscript.