despite this Comacchio slowly recovered. The Holy See later acquired the city and presented it to the archbishopric of Ravenna. In 1299, Emperor Rudolph I conferred it on Obizzo IV d'Este of Ferrara. In 1508 it became Venetian, but in 1597 was claimed by Clement VIII as a vacant fief. In 1598 the Papal States again acquired Comacchio and retained it until 1866 when it became a part of the Kingdom of Italy. The spread of malaria made the site unhealthy. Since then, most of the swamp land has disappeared, leaving ground for the expansion of agriculture, and creating new zones for dwellings. The area was the scene of fierce fighting during Operation Roast, which occurred in the last months of the World War II. Comacchio was formerly the seat of a bishopric and retains its cathedral, now a co-cathedral in the Archdiocese of Ferrara-Comacchio. The town was once home to a factory for sugar refining, which closed in 1988. Comacchio and its seafront Lidi are a centre for tourism. The town is noted in Italy for its practice of eel-fishing in the nearby wetlands, and many dishes served in Comacchio revolve around eel. Main sights Religious architecture Comacchio Cathedral (Duomo di Comacchio or Basilica di San Cassiano), dating back to the year 708 and dedicated to Cassian of Imola, originally comprised three naves, while today it has a single nave with twelve side chapels. The most notable artworks in the cathedral are the paintings by Biagio Bevi, the statue of the town's patron Saint Cassian, the wooden crucifix crafted by Germano Cignani in the 17th century and the organ built in 1728 by Gian Domenico Traeri. Adjacent to the cathedral stands the bell tower, designed by the architect Giorgio Fossati: it was built in 1751 but collapsed just a few years later, in 1757. It was later rebuilt and completed only in 1868 on the base of the old bell tower. Monastery of Santa Maria in Aula Regia: the current building, built in 1665, replaced the monastery of Santa Maria in Auregario, dated back to the 10th century. Of particular interest is the altarpiece of the high altar, late Renaissance work of a Ferrarese craftsman. The Loggiato dei Cappuccini, a 400 metres long arcade erected in 1647 in front of the building, was commissioned by the cardinal Stefano Donghi and is made up of 143 arches, each supported by