The naves of this hall-church have three cross-vaulted bays: in 1859, the Artari brothers, painters from Valle d'Aosta, enhanced the central nave with a decoration representing the four evangelists flanked by four prophets. Jacques Clérant and Claude Marin created the main altarpiece in 1698. In the centre of the altarpiece is a painting by Gnifeta (1859) representing the martyrdom of Saint Andrew: it is framed by twisted columns with vine branches and caryatid angels. They support an entablature surmounted by a Christ on the cross, flanked by Mary and Saint John. Angels show the instruments of the Passion or collect the blood in chalices. In 1708, Jacques Clérant and an unknown author sculpted the altarpiece of the Rosary in a naive style. Two twisted columns with climbing roses delimit the sculpted panel representing the Virgin and Child, accompanied by Saint Dominic and Saint Catherine of Siena. Several paintings adorn the side aisles.
- Historic site and monument