In the Imperial Age, many ports in Italy had been built in opus coementicium. The most important ones were in Latium (eg. Portus Romae, Antium and Centumcellae), in the Phlegrean Fields (portus Iulius, Misenum, Puteoli and Baiae) and along the northern-Adriatic coast (Classis-Ravenna, Aquileia and Altino). The military fleets of Augustus, in particular, were quartered in the ports of Classis and Misenum. Most Roman ports were located at river mouths and/or in lagoon areas and were connected with inland areas by rivers or artificial canals. For this reason, port structures (piers and...