Ancona, Ariminum and Ravenna, three Roman port cities overlooking a common Adriatic horizon: between political and commercial strategies, lifestyles and traffic, the analysis of their maritime dimension through five centuries of history, from the third century BC to the second century AD. The monograph provides a reading of the directions taken by Rome on the Middle-Adriatic in terms of ports. It is based on the analysis of the sources as well as on a close comparison, at several levels, conducted between the three facilities, the three cities and between these and other contemporary port areas of the Peninsula. Efficiency, functionality, relationship with the environment and infrastructures are only some of the parameters used for the comparison, while the port city is looked at as a place capable of incorporating the maritime dimension - in the urban characteristics, in the sphere of cults attested, in peculiarities that may prove to be a sign of a link between the inhabitants and the sea, in the mobility of individuals and in the activities practiced by them - in order to delineate a "contextual" reading of the coastal network of the Middle-Adriatic five centuries that contributes to a global historical reconstruction.