The bell tower dates from the eleventh and twelfth centuries and highlights the Romanic origins of the Cathedra. The oldest part is the base and the upper floors in gothic style were added in 1283-1284.

It is 43.5 meters tall. On the top of the tower a conelike structure holds the belfry. Similar bell towers can be found  in Ravenna dating from ninth century. This is evidence of the byzantine influence that was felt in the whole of northern Umbria.

There are other examples in the Tiber valley. There is anather in the town near the church of San Michele Arcangelo but it has been reduced and is now part of the rectory.