The Patriarchal Cathedral Basilica of Saint Mark, commonly known as St Mark's Basilica, is the cathedral church of the Roman Catholic Archdiocese of Venice, northern Italy. It is the most famous of the city's churches and one of the best known examples of Italo-Byzantine architecture. Originally this building was to be an extension of the Doge’s Palace, however the construction of the Basilica of St. Mark, which began in 828 and ended in 832, was made to house the body of St. Mark the Apostle brought from Alexandria to who they named protector of the city. This was a fundamental fact for Venice to be constituted as an independent episcopal seat.