Ancient Ostia presents the largest amount of urban mithraea in the Roman world. Although the city has not yet been excavated in its entirety, every known district has worship places dedicated to god Mithras. After the publication of Giovanni Becatti’s catalogue in the “Scavi di Ostia” series, the research carried out by the Ostia Marina Project of the University of Bologna has led to the discovery of a new mithraeum – so-called of “Colored Marbles” – built in the second half of the 4th century A.D. in the neighborhood outside Porta Marina. From this discovery, a research project has been proposed, aimed at a new systematic study of Ostian mithraism, in an attempt to understand its final stages of life as well as the decline and abandonment of the mithraea between the 4th and 5th century A.D., especially in connection with the victory of Christianity and its radicalization in the ancient city. On this occasion, some research will be presented, focusing mainly on the mithraea Aldobrandini, of Fructosus, of the Painted Walls, of the Snakes and of the Thermae of Mithra, with special attention to the new structural reliefs, carried out with modern bi- and three-dimensional techniques, and to the analysis of still unpublished archival materials
