The castle of Rogoi stands on the ruins of the ancient port of Bouchetion, founded in the 7th century BCE. Around 500 CE the shoreline began to move south as the river silted its delta. The Louros, which was navigable for the small ancient vessels, continued to flow through the developing swamp, but at some point in the medieval period the Byzantines decided to restore the fortifications that had been destroyed by the Romans, when they conquered Epirus in 167 BCE. In order to improve the defences, maintain access to the sea, and drain the marshes, the Byzantines artificially diverted the river to flow north, beneath the castle, and then west and south to the sea.