Of early Christian origin, but rebuilt in the Middle Ages the Church, initially in Romanesque style, it was enlarged in the early fifteenth century under Francesco I Gonzaga. The mixtilinear marble facade, with porch, rosettes and pinnacles was designed by Jacobello and Pierpaolo di Masegne. In 1545, the Cathedral was restored by Giulio Romano, which left intact the facade and perimeter walls but substantially modified the interior. At his death followed a long interruption of the work, then resumed under the guidance by Giovanni Battista Bertani. The current facade, fully marble, was built between 1756 and 1761 by Nicholas Baschiera: is salient, with three portals in the central part, topped by a triangular pediment. Along the right side you can still see the spiers and pinnacles of the fifteenth century. The interior of the Cathedral has a Latin cross, divided into five naves by four rows of Corinthian columns. Along each of the two aisles opens a row of chapels, whose altars are adorned with blades of the most important artists of Mannerism in Mantova. The dome, with octagonal drum, is painted inside with scenes of Paradise. Among the works of art there are also an early Christian sarcophagus, the frescoes of the baptistery (XIV century), the Chapel of the Incoronata and the Sacristy (formerly Chapel of the Voti), with the frescoed vault by a follower of Mantegna. The altar is made of polychrome marble, surmounted by a wooden sculpted crucifix.