This cathedral dating from the 13C and 14C has an elegant façade which is remarkable for its harmonious proportions and variety of openings. It was designed by Matteo da Campione, one of the maestri campionesi who spread the Lombard style through Italy. Inside the building, don't miss the splendid altar decoration and the chapel dedicated to Queen Theodolinda, adorned with attractive frescoes. The chapel houses the famous iron crown, a piece of goldwork thought to date from the 8C which, according to legend, was made from one of the nails taken from Christ's cross.