The tomb and mortal remains of the pope St. Leo the Great. Above the altar where he is buried, there is a majestic, high-relief marble portrait of Leo the Great as he met Attila the Hun, the scourge of god, near Mantua. The Pope's words were convincing, Attila was persuaded not to attack Rome. He told his troops that when the Pope spoke he saw the threatening figures of Peter and Paul with drawn swords before him. The sculpture was done by Alessandro Algradi (1595-1654) and is the only high relief of this type in the Basilica.

Altar of the Lie This altarpiece is a mosaic work representing The Punishment of the Couple Ananias and Saphira, from the original painting Cristoforo Roncalli (known as the "Pomarancio" of 1604. After lying to St Peter, Saphira fell to the ground before the Apostle; in the background two young men carry the dead body of her husband, Ananias.

Monument to Pope Pius VII was created by the Danish sculptor Thornwaldsen There is a statue on either side of the monument. Wisdom, crowned with an olive wreath and with an owl, symbol of Christian vigilance, at its feet, acquires knowledge from the Bible. Fortitude is dressed in a lion's skin and treads on a club. These are the two virtues that distinguished the troubled times of this pope's long reign.