Archbasilica of St. John Lateran
When he was seven years old, Antipope John XXIII made him a canon of the Archbasilica of St. John Lateran. He resigned this canonry during the pontificate of Pope Nicholas V, who made him "economous" of St. Peter's Basilica. He served as "Abbreviatore de parco maggiore" under Pope Eugene IV; as corrector of papal letters under Pope Pius II; and as papal datary under Pope Paul II.