Campanile
The early campanile with the circular base has never been rebuilt, although from the 13th century onwards it has often been suggested that it should be, and the ancient internal structure is still visible.
The bell tower accommodates the bell known as "La Nonna", which at a weight of 3300 kilograms is the largest bell that can be rung by the Bolognese method of bell-ringing.
Read more about this topic: Bologna Cathedral