According to the legend, Donnino was a Roman soldier close to the Emperor, who was martyred in the 4th century. After being beheaded by the Emperor’s guards on the banks of the Stirone River, he stood on his feet and walked to the other side of the river, carrying his head in his hands. The place where he stopped became a holy place to Christians: on this site citizens built a small church, which was restored and enlarged in the 12th Century. It has been a Cathedral since the 17th century, when it became seat of the bishop.
The design of the Cathedral is attributed to the famous architect and sculptor Benedetto Antelami, who may have worked at it during his time away from Parma. The Romanesque facade shows a perfect symmetry, framed between its two side towers: this style, typical of Romanesque buildings in Northern Europe, is very rare in Italy.
The church shows the passage from a pure Romanesque style to an initial form of Gothic. The three-nave interior, for example, features clusters of tall pillars and pointed arches.
The relics of Saint Donnino are preserved in the crypt.