Some remains of the southern and western part of the 12th century city walls still stand on via Nino Bixio. There are three postern gates dating from the earliest period of this segment of walls in the southern part, while other more roughly executed openings are of later date. The Wall at the southwest corner is built in rough-hewn stone and adjoins a large round archway in dressed stones, called in old texts Porta S. Pietro.
Several stages in construction dating from the 13th and 14th centuries can be discerned along the remaining stretch of the southern walls, built in stone with parts in brick, like the battlements.
In several places, such as those in brick with sandstone blocks here and there, repairs were carried out in the modern age or are contemporary, while the irregularlyshaped repairs in the lower part of the central portion of the walls are original.
In 2005, during excavations to build an underground car park in Piazza Vittorio Emanuele, at the eastern extremity of via Bixio, remains of the ancient city gate, porta di S. Gilio (or St. Egidius) , and the bridge leading to it, were unearthed. These remains, dating from the 12th century, abutted on to the southern extremity of the street of the same name (carraia san Gilio, now corso Italia) that in the early middle ages led to the main crossing of the River Arno.