The current walls date back to the Middle Ages and have been repeatedly reinforced. Of the original eight gates three still remain: the Saint Lucia gate, Porta Napoletana and Porta Romana.
Porta Napoletana was built in 1511 by labourers from Lombard and impresses with its size. In 1596 on the door was inscribed “You pay toll” (Si paga gabella) by the Congregazione del Buon Consiglio. Now it houses the local headquarters of the AIS (Italian Sommelier Association).