The Patriarchal Cathedral Basilica of Saint Mark, commonly known as St Mark's Basilica, is the cathedral church of the Catholic Patriarchate of Venice. It is dedicated to and holds the relics of Saint Mark the Evangelist, the patron saint of the city.

The church is located on the eastern end of Saint Mark's Square, the former political and religious center of the Republic of Venice, and is attached to the Doge's Palace. Prior to the fall of the republic in 1797, it was the chapel of the Doge and was subject to his jurisdiction, with the concurrence of the procurators of Saint Mark de supra for administrative and financial affairs.

The present structure is the third church, begun probably in 1063 to express Venice's growing civic consciousness and pride. Like the two earlier churches, its model was the sixth-century Ch ...