In the entire area of the Princes’ Palace, the most relevant information about the Roman era has been obtained concerning the southern enclosure of the legionary fort (XIII Gemina). It preserves, in some places, its entire original structure composed of massive stone blocks.

Another certain Roman construction is a barracks of which only a part remains, presenting a rich inventory of artifacts (tile fragments with graffiti and statue fragments). In the area investigated in 2020, foundations of a stone building and an older wooden one were identified, most likely attributable to the legionary barracks area. On-site, archaeologists also discovered various traces, such as those of a columned arcade gallery, from which only column bases and column shaft fragments remain.