Tomb of Antipope John XXIII

The marble-and-bronze tomb monument of Antipope John XXIII (Baldassare Cossa, c. 1360–1419) was created by Donatello and Michelozzo for the Florence Baptistry adjacent to the Duomo. It was commissioned by the executors of Cossa's will after his death on 22 December 1419, and completed during the 1420s, establishing it as one of the early landmarks of Renaissance Florence.

Source: Wikipedia — Tomb of Antipope John XXIII (CC BY-SA 4.0)