We are on the northwestern corner of the Roman defensive wall. If we continue South, along the dirt road to the river Natissa, we follow the path of the western walls, of which only very few remains are visible. This stretch of wall delimited the area of the city dedicated to public life; the area to our left hosted in fact the great Roman public buildings: the circus, the theatre, the baths and the amphitheatre. The presence of these imposing buildings and secular unbroken continuity of population of Aquileia determined the difference in level still visible between the city centre and the surrounding countryside, which is much lower
The defensive wall structure of Aquileia was modified several times over the centuries. The first ring, built in the Republican era (second century B.C.), had a rectangular shape and was set along the north-south axis. Access to the city was allowed through gates located on all sides of the city walls that, in addition to security, also had the task of transmitting the image of the greatness of the new colony, which is why they had a monumental aspect and were enriched by sculptural decorations, such as large clay sculptures now on display in the porches of the National Archaeological Museum. During the first century B.C., Aquileia experienced a great economic and urban development. New buildings were created beyond the perimeter of the Republican walls, which were gradually dismantled. The political stability of the early imperial age allowed the town not to have a city wall for a long time
The new city, much wider than the previous one, was built from the end of the third century using a lot of recycled materials. The imperial walls, which are also impressive, managed to defend the city for months during the siege of Attila in 452, but in the end Aquileia was conquered. After this disastrous event, which marked the beginning of the collapse of the entire Roman Empire, the northern part of Aquileia was slowly abandoned. New defensive walls were built in a recessed position, along the Maximum Decuman, today known as the saw tooth Late Ancient walls, for their characteristic structure along a broken line.
From this point, which corresponds to the northwest of the Roman Aquileia, the Via Annia, one of the main and oldest roads connecting the city of Aquileia to Italy started. From here, it continued westward, touched Padua and then joined the Via Emilia. The via Postumia, built in 148 B.C., went up northward to Palmanova and then split into two parts: one headed to Concordia and then to Oderzo, the other continued straight touching Tricesimo and over the Alps to the Monte Croce Carnico Pass. To the east, in addition to the road leading towards Trieste and the Istrian coast, there was also the Via Gemina, which went beyond the Isonzo near Gorizia to advance towards Ljubljana
The archaeological investigations have revealed various portions of Aquileia's road network, built since the time of the founding of the colony, but subjected to constant maintenance and restoration. Currently we can see, to the south of the forum, a section of a main road that served as a link between the port and the forensic complex (the so-called decuman of Aratria Galla) while, in the excavations that can be visited north of the Christian basilica (former Cossar funds), we can see the remains of another road, once lined with some houses.
The Ponte Rosso area is so named after the colour of the bricks of the original bridge. The river flowing under this bridge is the Terzo river, called Robedula in the Middle Ages, which today marks the border between Aquileia and Terzo. This entire area, which originally was a marshland, was reclaimed in the second half of the eighteenth century and is known as III Partita