This paper considers a group of stone mortars found during excavations in the area of the Theatre of Marcellus at the end of the 1920s. The interest in this group of mortars derives from the fact that examples of similar size present carving lines that can be connected with different steps of their production. These factors and their discovery in a specific context have led us to believe that we are in the presence of the products of a workshop located in the Theatre of Marcellus. The limited morphological evolution of the mortaria over the centuries does not allow for a precise dating. However, the evidence of mortars reworked from original capitals dating back to the fourth-fifth centuries AD allows us to consider this period as a terminus post quem. The activity of the workshop dedicated to the production of marble mortars can therefore be included among the commercial activities that gravitated around the ancient Portus Tiberinus around the ninth century.
