The 13th century walls, in addition to the three main gates that replicated the names of the Roman gates from which the name of the sestieri (districts) of porta Romana de intus and de foris, Porta Cintia de supra and de suptus, porta Accarana – corruption of the ancient name Herculana – de supra and de suptus originates, were interspersed by numerous doors and posterns that facilitated the circulation of men and goods between the city and the countryside.

Among these, the ancient Porta San Giovanni, which owes its title to the original church of St. Giovanni in Statua, connected to the walls through the steep via Pennina, is still visible with its 16th century infill.

A drawbridge allowed the crossing of the defensive moat in front of it.