Mapping monumentality in a Roman colony: A non-invasive archaeological approach to the forum of Colonia Salaria (Spain)

• Integrated survey reveals urban planning in a previously unexplored colony. • Terraced opus caementicium architecture defines a hierarchised colonial forum. • GPR detects subsurface alignments consistent with public architecture. • Surface artefact patterns distinguish civic and domestic activity zones. • Digital enhancement of historical aerial photos improves architectural detection. Roman colonies played a key role in the articulation of imperial power, yet many remain poorly understood due to limited excavation, long-term land use, and methodological constraints. This paper addresses how early imperial colonial urbanism can be reconstructed, and how monumental civic spaces were spatially, architecturally, and symbolically configured in colonial contexts. Focusing on Colonia Salaria (Úbeda la Vieja, Jaén, Spain), the only Roman colony in Hispania never systematically investigated, this study applies an integrated non-invasive approach to analyse its forum . The research combines UAV-based photogrammetry, high-resolution systematic surface microsurvey, ground-penetrating radar (GPR) and digital enhancement of historical aerial imagery. Microsurvey provides spatially explicit data enabling functional differentiation between sectors, which, when integrated with the analysis of emergent architecture, reveal extensive marmorised, hierarchised terraces constructed predominantly in opus caementicium and organised into two monumental enclosures. Digital enhancement of historical aerial photos improved architectural detection. GPR data further reveal subsurface alignments, dense construction deposits, and possible collapsed substructures consistent with a cryptoporticus. The results identify a formally structured monumental space compatible with a closed or bloc-type colonial forum with an annexed monumental complex. Overall, this study shows how integrated non-invasive methodologies can reconstruct complex urban and monumental configurations, providing new insights into the materialisation of Roman imperial dominion over pre-existing Iberian oppida through the strategic articulation of architecture and topography.