Founded in 1064 and consecrated with great pomp on September 26th 1118, the Cathedral was built in two stages, one by architect Buscheto, who created the original layout with the basilican body with four aisles and one nave, a transept with one nave and two aisles, and the dome on the cross vault, and one by Rainaldo, who extended the building and the façade. The building was not finally completed until the last quarter of the XII century, when Bonannoís bronze leaves were placed on the central door, which were later destroyed by the devastating fire of 1595, after which many of the destroyed works were replaced and a vast decorative plan was started.