Mosaic of St. Teresa de Jesus by the tomb of Pope Pius XI (d.1939) in the left aisle of the crypt, near the Confessio. The effigy of the pope was sculpted by Giannino Castiglioni and the tomb is made of the marble used to build Milan Cathedral. The arcosolium (arched niche) is decorated with Ravenna-style mosaics based on designs by the painter Pietro d'Achiardi. In the center is Christ Pantocrator, flanked by angels and labeled with the inscription REX REGVM, PRINCEPS PACIS (King of Kings, Prince of Peace). On the sides are St. Ambrose, patron saint of Milan, and St Teresa of Jesus, who was canonized by the pope.