On the balconies Bernini created showcases , framed by the eight ancient twisted columns , to display the four most precious relics of the basilica : the spear of Longinus , said to have pierced the side of Christ , the veil of Veronica , with the miraculous image of the face of Christ , a fragment of the True Cross discovered in Jerusalem by Constantine 's mother , Helena , and a relic of St. Andrew , the brother of St. Peter .
The basilica owns some precious relics : a piece of the True Cross of Jesus , a veil that a woman wiped the face of Jesus with , while he was carrying the cross , the spear that was used to pierce Jesus side , and the bones of St. Andrew , the brother of St. Peter .