Materials collected during a survey by the Gruppo Latino Ricerca Subacquea in the area of the massif of Artemisio and the adjacent hills show that these areas were occupied in the Bronze Age and the Orientalizing and Archaic periods, with sporadic occupation in the Roman and Medieval periods. The hypotheses that residential and cult areas existed in the central part of the massif encouraged its excavation. A rich deposit of Medieval materials (12th - 14th centuries) was revealed, along with a structure of rectangular form filled with a collapse of tiles from the first phase and by strata containing late-Orientalizing and Archaic materials. The oldest materials are datable to the final phase of the Bronze Age and the Early Iron Age and relate to an earlier activity cut by the walled structure. The continuation of this research will allow us to test the hypothesis that the structure is datable to the seventh - sixth century BC, the period to which the tiles in red impasto discovered on the interior appear to date. The Medieval materials, instead, could be related to the activities of the religious complexes recorded between the 11th and 14th centuries in the neighboring area of Peschio. The origin of the toponym Artemisio is also interesting, as it is apparently related to the consecration of the northern area of the territory of Velletri to the cult of Diana, mentioned by the sources. However it is only documented in cartography since in the 1600s. (Luciana Drago)