The exterior is notable for the geometric patterning of its revetment, made from encrusted marble. It mimics the Tuscan Romanesque style of the revetment on the baptistery. It should be noted that the facade of the cathedral does not date to the Renaissance, but instead to the 19th century. Unlike in countries to the north, facades in Italy were considered to be lesser in importance and were put on at the end – and in this case, several centuries after the rest of the church was already built. We can also see how the revetment was carried over into the bell tower which stands next to the cathedral.