The Santerno is a river of RomagnaAlthough its first kilometers are geographically in the Tuscany region., northern Italy, the major tributary of the Reno River. In Roman times it was known as Vatrenus (small Renus), although in the Tabula Peutingeriana is already mentioned as Santernus.It rises near the Futa Pass, at 1,222 m of elevation, in the Apennines ridges facing the plateau of Firenzuola. After Firenzuola it flows in Castel del Rio, where it is crossed by a famous medieval bridge Po