Consecrated in 1027, the basilica became the abbey church of the Benedictine monastery founded on 9 July 1029 by Olderico Manfredi, Marquis of Turin with his wife Berta and brother Alrico, Bishop of Asti. It became the cathedral of the Diocese of Susa in 1772. The building was extended in the 12th century, when a storey was added and the church’s façade was set against the city walls. Further construction work was carried out on the apse, which was rebuilt in Gothic style from 1321 due to its critical state of repair during a period of economic hardship for the authority. The Gothic spires and terracotta crown of the campanile and façade pinnacles were added in the late 1480s by Cardinal Guillaume d’Estouteville, Commendatory Abbot of San Giusto. Most of the current side chapels were built in the Late Baroque period. The decoration of the building as it appears today dates from 1863–65, when Edoardo Arborio Mella commissioned the Neogothic scheme. The gabled façade is distinguished by a simple stone portal and pinnacles and a brick Lombard band at the top. The southern façade of the cathedral is characterized by the imposing bell tower, built at the same time as the original construction. The exterior is decorated with a series of fresco cycles painted between the 12th and 15th centuries: a lunette, unaligned with the current side door, houses the Crucifixion, while the portal of the adjacent wall is adorned with the crest of Cardinal d’Estouteville. Christ’s Entry to Jerusalem is depicted on the entrance on the southern façade, while fragments showing scenes of the Life of Saint Maurus and figures of prophets have been found by the large arch next to it. The building has a nave and two aisles, covered by cross vaults. The nave ends in a semicircular apse, while the aisles terminate in two chapels. The chancel is raised by a few steps, and the little bishops’ crypt is situated below it. The chancel is also home to the choir, a rare example of 14th-century wood carving, in the form of 18 large stalls set against the apse and part of the original small stalls (some have been converted to kneelers). The pediment depicts the theme of the Mystic Hunt, derived from medieval bestiaries, with a hunter and an angel blowing horns either side of a flight of animals, with many small monstrous figures among them: an allegory of discernment between good and evil. The baptistery is located next to the southern side of the transept, and houses a 16th-century wooden crucifix and the great 12th-century baptismal font, carved from a single block of green Cesena marble. On the northern side of the transept we find the sacristy and the chapter room (both normally closed to visitors). The latter houses the 12th-century marble altar signed by Peter of Lyons. The cathedral’s wealth of artworks includes the late 15th-century triptych of the Virgin and Child with Saints Hugh of Lincoln and Hugh of Grenoble on the relic altar and the great altarpiece with the Stories of Saint Nicholas in the sacristy. The fine Baroque furnishings include the Saint Anne altarpiece by Guglielmo Caccia, known as Moncalvo, the Immaculate Conception altarpiece attributed to Antonio Maria Viani, and the statues of Saints Peter and Paul in the Chapel of the Crucifixion (1710) commissioned from Etienne Fodéré. Another noteworthy work is the wooden statue of the Magdalene against the wall of the southern aisle, which local tradition long identified with Countess Adelaide of Susa. The Cathedral Treasure is on display in the Diocesan Museum of Sacred Art and includes part of a chasse reliquary made by barbarian craftsmen (7th century), the door-knockers of the old cathedral portal (c.1130), the Rocciamelone Triptych (1358), and the processional cross by Johannes Bos (c.1360).