To the south of the civil basilica and the decuman next to it, the remains of an imposing fortification wall emerged, consisting of a sequence of triangular bastions that follow a broken line.

This new defensive line, reachable to the west by a road, and placed to defend the town that developed around the basilica complex, led to the abandonment of the entire northern part of the Roman city, starting with the Forum.

To the east, the walls were connected to the previous late antique wall circuit, while, in correspondence with the main north-south road axis of Roman Aquileia, the city gate opened. This new wall was recently assigned to the 6th century, after the Greek-Gothic war (535-553 AD) and the Byzantine reconquest.