The current façade is unfinished, with a 16th-century covering on the lower level, with pilasters surrounding niches containing the statues of the four patron saints of the city.

In February 2009 it was announced that a Roman mosaic floor filled with scenes depicting pagan rites and oriental gods had been discovered underneath the cathedral.

The size and design of the mosaic pavement suggest that it formed the floor of a huge room.

[1] The mosaic pavement has become an important piece of the Museo Diocesano (Museum of the Diocese), which exposes also fragments of ancient churches, dating back to the times of Matilde di Canossa, and a medieval bas-relief (Christ in throne amidst angels), originally located in the main altar of the cathedral.

There are also works by Carlo Bononi, Francesco Vellani, Sebastiano Vercellesi, and Orazio Talami, whilst Annibale Carracci's The Virgin Appears to Saint Luke and Saint Catherine originally hung in the cathedral's notaries' chapel.