Roman baths are not only fascinating architectural structures but also provide many insights into the ancient culture. They represent an emblematic step in the process of civilization, indicative of the importance of cities or the families that had them built. Their heating systems exemplify the outstanding level of technological progress achieved by the Romans. A novel interdisciplinary methodological approach is present-ed to bridge the knowledge gap that often still concerns Roman baths. It integrates in-situ analyses, laser scanning surveys, thematic 3D models, computational fluid dynamics simulations, thermoluminescence, and optically stimulated luminescence dating, providing an in-depth investigation of the 3D spatiality, the functional layout, the construction techniques, the operation, and the diachronic development of thermal complexes. In this paper, the proposed approach is applied and validated on one of the best-preserved thermal buildings anywhere in the Roman Empire: the Indirizzo baths at Catania (Sicily). The dating campaign confirmed that the complex was built at the end of the IV century and stayed in operation until the VII century. The outcomes are a fundamental premise for future conservation and exploitation activities, while the proposed methodology constitutes a useful approach that can be effectively replicated to better understand and promote other Roman thermal complexes.