[1] The interior is subdivided into spaces for the general public and for the friars, separated by a partition wall (tramezzo), supported by three round arches.
In the cosy atmosphere of the church, with the gothic arches sustaining the ceiling trusses, the wall of frescos by Gaudenzio Ferrari are one of the masterpieces of Renaissance painting in Piedmont and Lombardy.
They depict the life and passion of Jesus Christ on a surface of 82 m2 (880 sq ft): twenty equal frames narrate the main facts told by the gospels from the Annunciation to the Resurrection, working as Biblia pauperum.
The most important model was Giovanni Martino Spanzotti, author of a similar decoration in the church of San Bernardino in Ivrea.
Despite the importance of his models, Ferrari also painted some figures (such as armors, horse heads, halos) in relief to give them particular prominence; an innovation perhaps prompted by the three dimensional tableaux of the Sacro Monte chapels.
In the aisle is a fresco on the left wall, near the pulpit, by Fermo Stella, Ferrari's apprentice, who worked with his maestro at the Sacro Monte.