This work presents the results of the architectural survey, performed with the Leica P20 terrestrial scanner, in the cathedral of St Cesareo in Terracina, thanks to the collaboration between the Department of Classics and the Department of History, Anthropology, Religions, Art and Spectacle of Sapienza University in Rome. The interaction of experts in various disciplines (History of Art, Archaeology, Architecture) with the use of this technology made possible a new and detailed documentation of the building, and allowed us to investigate with more data some of the critical issues addressed by scholars in the past years, such as the relationship between the various construction phases, the presence of the Roman temple and the constructive relationship between the portico and the bell tower.