The Basilica of Saint-Romain in Blaye was an important Merovingian basilica, the resting-place of Charibert II, a son of Clotaire II who was briefly king of Aquitaine from 629 to his death in 632, and of his son. According to the 12th-century Chanson de Roland contained the body and relics of the Carolingian folk-hero Roland, who was a seigneur of Blaye in the eighth century.
The nominal patron of the basilica, belonging to the Canons Regular of Saint Augustine, remained the local 4th-century martyr Saint Romanus of Blaye; here the pilgrims bound for Santiago de Compostela paused before taking to boats to cross to Bordeaux.
In 848, the fort and its surrounding habitations were laid waste by the Viking chief Hasting.
Some vestiges of the structure remain within the Vauban fortress at Blaye, which formed part of the traditional defenses of the Gironde estuary.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.