The Bolonia Bay, close to the Strait of Gibraltar, hosts the Roman ruins of Baelo Claudia. In the first and third century A.D., this ancient town was affected by two earthquakes. Several earthquake-related damages can be found inside the ruins, and the adjacent mountain ranges show features of Quaternary activity. Extensive paleoseismological and archaeoseismological investigations have been conducted at the archaeological site and in its environs. The first ¹⁴C dating results from damaged infrastructure are presented in this paper, together with the preliminary results of fault-trenching on one of the closest suspect seismogenic faults near the archaeological site. The observations have been quantified using the two logic trees for paleoseismology and archaeoseismology. Our results show that a mere paleoseismological classification of the geological features leads to a paleoseismic quality factor (PQF) of 0.03, which is low compared to other studies. Taking into account the additional information from archaeoseismological work (archaeoseismological quality factor [AQF] is 0.5), it becomes clear that the Baelo Claudia study site provides an opportunity for detailed earthquake investigations. Therefore, it has a high potential for reliable seismic hazard analyses. A complementary application of both logic trees is recommended in future studies if sufficient data are available.