Low-Frequency GPR as a Gateway to Archaeological Investigations: The Aeclanum’s Buried Roman-age Forum (Southern Italy)

Ground Penetrating Radar (GPR) is a cornerstone technology in archaeological research due to its ability to non-invasively detect subsurface structures and artifacts. By emitting electromagnetic waves and analyzing their reflections, GPR enables researchers to map buried features with high precision while preserving the site's integrity. Low-frequency GPR systems, in particular, are well-suited for archaeological contexts, offering the depth penetration required to investigate complex stratigraphic settings and revealing structures that might otherwise remain undetected. The Archaeological Park of Aeclanum, located in Mirabella Eclano (AV), Southern Italy, is a site of great historical importance, hosting remains of a city that flourished under the Samnite and Roman civilizations. Among its most significant areas is the ancient Roman Forum, once the political, religious, and commercial heart of the city. Despite its historical relevance, the Forum had not yet been uncovered, and its exact layout and architectural features remained unknown. Previous investigations using higher-frequency GPR systems were limited in depth penetration, failing to detect deeper buried structures. To overcome these limitations, a low-frequency GPR survey was conducted in the Forum area. The survey employed a monostatic antenna with a center frequency of 80 MHz, enabling a maximum exploration depth of up to 5 meters, far exceeding the capabilities of previous investigations. This deeper penetration facilitated the identification of subsurface anomalies consistent with walls, pavements, and foundations. These anomalies provided the first geophysical evidence of the Forum’s layout and subsurface features, shedding light on a previously unexplored area. The GPR data revealed a series of significant anomalies, particularly at depths ranging from 1 to 3 meters. These features were interpreted as remnants of buried architectural elements associated with the Forum, including masonry walls, paved surfaces, and foundations. The ability to detect these features highlights the critical advantage of using low-frequency equipment in archaeological investigations. To validate the geophysical findings, targeted archaeological excavations were carried out in areas corresponding to the most prominent anomalies. These excavations uncovered well-preserved structural elements, including segments of masonry walls and paved surfaces, precisely matching the GPR-detected anomalies in location, depth, and geometry. Notably, the excavation confirmed the presence of foundational elements at greater depths, which were undetectable in previous surveys. The excellent spatial correlation between the GPR data and the exposed remains demonstrated the reliability and precision of the low-frequency GPR survey in reconstructing the Forum's layout. This study underscores the importance of selecting appropriate GPR configurations for specific archaeological objectives. By combining non-invasive geophysical techniques with targeted excavation, this integrated approach maximized the efficiency of the investigation while minimizing its impact on the site. The findings reinforce the potential of low-frequency GPR as a powerful tool in uncovering and preserving buried archaeological heritage.