Ravenna - Lakes, rivers and canals Fiume Montone About 90 km long, it was born at San Benedetto in Alpe. After having wet several major centers such as Portico di Romagna, Dovadola, Castrocaro Terme, Rocca San Casciano and Terra del Sole, in the one of Ravenna it receives the Ronco River and origins the United Rivers that flow into the Adriatic.