This data set contains ground-penetrating radar (GPR) data acquired at the Roman city Interamna Lirenas by Lieven Verdonck, between April 2015 and August 2017, within the ‘Beneath the Surface of Roman Republican Cities’ project. The area surveyed was approximately 23 ha. Data were collected with a pulse GPR and an RTK-GNSS instrument or robotic total station. The traverse separation was between 0.06 m and 0.12 m, the reading interval was approximately 0.05 m. The GPR data in this data set consist of georeferenced time-slices (GeoTIFFs), as well as shapefiles containing the delineation of the GPR anomalies by Alessandro Launaro, which were the basis for the archaeological interpretation. Both the GeoTIFFs and the shapefiles can directly be added to a geographical information system. Furthermore, metadata files in .csv format include all details on GPR data acquisition and processing, and on the creation of the shapefiles with the delineation. For the raw and processed GPR profiles in SEG-Y format, please refer to the open-access archive at the Archaeology Data Service (see the link below, under ‘Related resources’).