The aisles on either side of the nave house a total of six side chapels. Henri Révoil designed and Jules Cantini constructed the altars; Cantini also created the statue of Peter and made it a gift to the sanctuary. Each altar tomb features the coat of arms of its respective saint. The ceiling of each chapel is decorated with a mosaic, depicting the name and arms of the financer on one side and a symbol of the saint on the other.