Archaeological Excavation of the Ravne 6 Tunnel (Visoko, Bosnia and Herzegovina): Results from the 2025 Field Season

Abstract

Ravne 6 forms part of the Ravne underground complex near Visoko, Bosnia and Herzegovina (43˚59'44'' N; 18˚09'39'' E; 496.650 m a.s.l.). In 2025, a formally authorized stratigraphic excavation was conducted in this tunnel section for the first time. Work focused on documenting sedimentary infill, architectural features, and depositional relationships within a confined subterranean environment developed in conglomeratic deposits. Excavation proceeded manually following stratigraphic principles. All excavated sediments were dry sieved through a 5 mm mesh. Organic materials were recovered by hand using gloves and stored separately; no flotation was employed. The tunnel plan and excavation extent were recorded through a geodetic survey. The exposed sequence consisted of compact clay-rich deposits with rounded conglomerate inclusions, locally interrupted by dry-stone constructions, including a linear wall-like feature extending approximately 5 m along one section of the tunnel. Material recovered from documented contexts includes wooden artifacts and faunal remains. Several dry-stone structures were recorded in situ. Three wood samples (FTMC-DT95-1, 2, 3) were analyzed by accelerator mass spectrometry at the Vilnius Radiocarbon Laboratory. The conventional radiocarbon ages (415 ± 29 BP; 433 ± 28 BP; 402 ± 29 BP) calibrate to the late 15th-early 16th centuries CE (IntCal20, 2σ). These dates indicate phases of use or deposition during the late medieval period and relate specifically to the dated wooden material. The 2025 excavation provides a controlled stratigraphic and architectural record for Ravne 6 and establishes a documented empirical basis for continued investigation within the Ravne underground complex.