[2] Usually the new patriarch was a Venetian diplomat or administrator, as with Lorenzo Priuli in 1591 or Francesco Vendramin in 1608, though some were career clerics, who had usually been previously in positions in Rome, such as Federico Cornaro in 1631.

The Venetian islands at first belonged to the diocese of Altino or of Padua, under jurisdiction of the archbishop of Aquileia, believed to be the successor of St. Mark.

At the end of the invasion, many of the ancient dioceses of the mainland were restored by the Lombards, while the exiles supported the new sees in the lagoons.

In 774 or 775, Pope Adrian I and John IV, Patriarch of Grado, authorized the establishment of an episcopal see on the island of Olivolo.

[8] When the ship reached Olivolo island in Venice, the saint made signs (or so it was claimed) showing he did not want to be placed in the custody of the bishop.

Instead, he was taken to the doge's chapel, and planning began to create a magnificent new temple, St Mark's Basilica, suitable for such important relics.

[10] In 1084 the Emperor Alexios I Komnenos in his Golden Bull recognized the full independence of Venice, along with freedom from tributes, trade restrictions and customs duties.

An important role was played by the primicerio, based in Saint Mark's, who represented the doge and the city government.

The election of the patriarch belonged to the Senate of Venice, and this practice sometimes led to differences between the republic and the Holy See.

Giovanni Trevisan, OSB (1560), introduced the Tridentine reforms, founding the seminary, holding synods and collecting the regulations made by his predecessors (Constitutiones et privilegia patriarchatus et cleri Venetiarum).

Cardinal Giuseppe Sarto, afterwards Pius X, succeeded in 1893; he was refused recognition by the Italian Government, which claimed the right of nomination formerly employed by the Habsburg Emperor of Austria and in earlier times by the Venetian Senate, but after eleven months this pretension was abandoned.