CAORLE. – It is the Venetian island situated at the estuary of the Livenza, a refuge for the bishops of Concordia during the Lombard invasion at the end of the 6th century. Pope Deusdedit (615–618) is said to have established the diocese. In the year 876 mention is made of a bishop of C., Leo, excommunicated by Pope John VIII. Known bishops are then Marino in 919, John in 1053, Bono in 1074, and others. In 1247 Bishop Rinaldo consecrated the high altar in the 11th-century cathedral, which was later transformed and consecrated to St Stephen on 30 August 1663. Bishop Pietro Carli had rebuilt the church of St Nicholas and the episcopal residence in 1490. The last bishop was G. M. Peruzzi, appointed in 1795, who transferred to Chioggia after Pius VII, on 1 March 1818, suppressed the diocese, uniting it with the patriarchate of Venice.
The cathedral has three naves with alternating columns and piers, polygonal apses, and a circular bell tower of the Ravenna type. The high altar features a gilded silver altarpiece from the 13th century.