Probably founded in 903 and later destroyed by Hungarians, today's Basilica was built between the end of XI and the beginning of the twelfth century by Bishop Sigifredo. A restoration of Romanesque appearance and the demolition of Baroque additions took place since 1902, by Ettore Martini. During conservative works, valuable frescoes, dating back to the 17th century, are attributed to Giovanni Evangelista Draghi. In the presbytery there is a polychrome mosaic of the end of the 11th century, another of the same era is present in the Crypt and one still in the left nave. Romanic-Lombard style characterizes the interiors decorated with fine anthropomorphic, zoomorphic capitals, with monstrous and vegetal figures. On the main altar of 1764, a wooden crucifix was placed at the beginning of the twelfth century.