Ferrara's Renaissance walls are among the best-preserved in Europe. The 9-kilometre circuit, built in brick in the 15th and 16th centuries, completely encircles the historic centre and is topped for much of its length by a wide grass walkway and a tree-lined cycle path. You can walk or cycle the full circuit in a couple of hours, looking out over the moat and the flat Po plains beyond.
The northern stretch of the walls, from Porta Mare to Porta Paola, is the most rewarding: broad, quiet, and with views over the Renaissance districts of the Addizione Erculea. The walls are at their most atmospheric in the early morning before the cyclists take over, and in the evening when the locals use them as a passeggiata. Several of the original gate towers survive and can be visited.