The eight side altars, embellished with marbles, stucco decorations, columns and paintings are devoted to St. Joseph and St. Erasmus, patrons of sailors, smiths and paper makers.
The high altar, where stands the Crucifix by Maragliano and with the splendid canvases by Assereto on its sides , is embellished by the marble antependium by Solaro and Orsolino, dating 1632.
The vault of the inner dome was frescoed in 1866 by the painter Francesco Semino.
The impressive Mascioni organ has been housed in the apse since 1961.
The church owns a beautiful Genoese crib with wooden statues of the 18th century by Maragliano school and visible during Christmas period.
The ark of the procession, the work by A. Brilla from 1874, with the plastic representation of the martyrdom of Saints Nazario and Celso is exposed during the patronal feast (July 28th).