Conimbriga: A Comprehensive Geophysical Survey and the Reconstruction of the Town’s Plan

In the summer of 2022, a large-scale geophysical survey was conducted in the Roman city of Conimbriga (Condeixa-a-Nova, District of Coimbra, Portugal). An area of 7.32 ha was covered with magnetic measurements using the CMP 7-probe fluxgate gradiometer array, combined with a GNSS-RTK positioning system. At the same time, an area of 0.9 ha was investigated using the IRIS HI–MOD (IDS) system, equipped with five 600 MHz antennas and also combined with a GNSS-RTK system. In addition, several soil samples were taken to determine their magnetic susceptibility and electrical conductivity. The most important conclusion of this survey campaign is that the geological and archaeological conditions in Conimbriga present significant challenges for both magnetic and GPR prospection. Despite these limitations, this large-scale dataset allowed for the identification of monumental building complexes across the entire intramural area, as well as the distinction between city quarters and ancient infrastructure. Following this identification, an exercise in archaeological interpretation was applied to the geophysical evidence, combining it with existing knowledge of the excavated area of the town. The results of this endeavour led to the interpretation of the identified structures as part of a palimpsest of four main periods of urban development. The reliability of this interpretation can be confirmed by verifying the proposed results through targeted archaeological analyses, which will be a future project of major importance.