The Benedictine Abbey was founded in the early 11th century by Guglielmo da Volpiano. Around 1400 suffered a period of decline that followed the Suppression; in 1585 it was transformed into a collegiate church. Vittorio Amedeo delle Lanze, in 1770, built on a project attributed to Bernardo Antonio Vittone, a new large church whose system overlaps with medieval structures.
The original building had three naves Court cut by a transept which opened five apsidal chapels: with multiple altars so many monks had the chance to celebrate the liturgy. The walls of the transept chapels preserve colorful f