Lanciano has been an important trading centre ever since the late Empire when it was famous for its fairs and for commerce in general. During the medieval and modern eras the town’s annual fairs - held in June and in September - were the most celebrated in central Italy:  Merchants attended, not only from every part of the Italian peninsular, but also from France, central Europe and also from across the Adriatic in the Balkans. Merchants and visitors would enter the city through the numerous gateways located along the town walls. The Porta Diocleziano has medieval origins and its history is linked to the development of the Lanciano town walls. Today it is the junction that connects Largo Paolo Tasso with the Diocleziano Bridge. The higher part seems to have been added in a later era. The door provided with a single opening is constructed in open brickwork excluding the base of the arch imposts that are made of stone and bricks. The entrance room is in a trapeziform shape, its vaulted ceiling is framed by a segmental arch, wider on the external side, A level-marking cornice, positioned above the arches separates the entrance from the level above. Above the single opening the two facades form a rectangular room occupied by a window leading from a balcony to the inside.