It rises near the Futa Pass, at of elevation, in the Apennine ridges facing the plateau of Firenzuola in the province of Florence. Beyond Firenzuola, it flows northeast through the province of Bologna near Castel del Rio, where it is crossed by a famous medieval bridge, the Ponte degli Alidosi. It then flows past Fontanelice, Borgo Tossignano, Casalfiumanese, and, once in the Pianura Padana (the Po River's valley), Imola. The river forms the border between the province of Bologna and the province of Ravenna for a distance before entering the province of Ravenna. It then empties into the Reno near Argenta.