The works for the restoration of the cathedral were started in 1773. In this preliminary phase, part of the artistic choices was made by canon Giuseppe Antonio Gromo, general Vicar of the diocese, on the occasion of the arrival of Bishop Giulio Cesare Viacini. The choice of a Gothic revival style not only parallels other contemporary monuments from Piemonte and Lombardy, but was also considered as the aptest because of the strong 'return to the origins' of the doctrine of those years. The first phase of the restoration of the cathedral – from 1772 to 1803 – includes the enlargement and building of the two side aisles, and of the four chapels (two on each side), alternating with four square rooms; the positioning of the ends of the two side aisles, the creation of the sacristy and of the capitular room, the placing of the two chapels opening up at the side of the transept ('Epiphany' on the left and 'Sacrament' on the right), the building of the Canons' and Bishops' sepulchres underground. As far as paintings are concerned, the apsis, the dome and the presbytery were all decorated. In 1795, Giovannino Galliari completed the perspective of the right part of the presbytery, while in 1784 Carlo Cogrossi carried out the large altarpiece in the apsis, representing the Assumption of the Virgin. In the second phase of the restoration, conversely, the works focused on the creation of further chapels: Madonna delle Grazie, Dottrina Cristiana, Annunciazione and Immacolata; then on the prolongation of an arcade in the nave and the addition on the facade, of Felice Marandono's pronaos. Among the architects who interved in this second phase, one of the most important is Nicola Martignano Tarino, frequently mentioned in the projects for the building of bridges and roads in the surrounding countryside. The second phase of the pictorial decoration of the cathedral was devoted to the completion of the aisles and of the lateral chapels.
