Marco Barbo of Venice was a cousin and lifetime follower of Cardinal Pietro Barbo, who became Pope Paul II in 1464. Marco was appointed Bishop of Vicenza on 17 September 1464; appointed a cardinal of the Roman Catholic Church on 18 September 1467; and Patriarch of Aquileia in 1470. He was a principal papal administrator.

The Diocese of Vicenza is a Latin diocese of the Catholic Church in Italy. It is located in the region of the Veneto, and is the capital of the Province of Vicenza, approximately 60 km west of Venice, and around 45 km east of Verona. The diocese was in existence before 590. Vicenza was a suffragan of the Patriarchate of Aquileia until 1751. In 1751 it was transferred to the ecclesiastical province of Udine. In 1818, upon the dissolution of the ecclesiastical province of Udine, Vicenza was made it a suffragan of the Patriarchate of Venice.