Basilica of Aquileia (2) Cripta Degli Affreschi E Mosaici
According to Wikipedia, Aquileia used to be the ninth among the great cities of the world, placing Rome, Mediolanum, Constantinople, Carthage, Antioch, Alexandria, Trier, and Capua before it. However, such prominence made it a target and it was besieged by Alaric and the Visigoths in 401, during which time some of its residents fled to the nearby lagoons. It was again unsuccessfully attacked in 408 by Attila, who returned in 452. During this second invasion, the city was so utterly destroyed by Attila and his Huns that it was afterwards hard to recognize its original site. the fall of Aquileia was the first of Attila's incursions into Roman territory, followed by cities like Mediolanum and Ticinum. The Roman inhabitants, together with those of smaller towns in the neighborhood, fled en masse to the lagoons, and so laid the foundations of the cities of Venice and nearby Grado.
Yet Aquileia would rise again, though much diminished, and continue to exist until the Lombard invasion of 568. It was once more destroyed (590) by the Lombards. Meanwhile, the patriarch fled to the island town of Grado, which was under the protection of the Byzantines. When the patriarch residing in Grado was reconciled with Rome in 606, those continuing in the Schism of the Three Chapters, rejecting the Second Council of Constantinople, elected a patriarch at Aquileia. Thus, the diocese was essentially divided into two parts, with the mainland patriarchate of Aquileia under the protection of the Lombards, and the insular patriarchate of Aquileia seated in Grado being protected by the exarchate of Ravenna and later the Doges of Venice, with the collusion of the Lombards. The line of the patriarchs elected in Aquileia would continue in schism until 699. However, although they kept the title of patriarch of Aquileia, they moved their residence first to Cormons and later to Cividale, which we visit tomorrow.