After the fall of the Roman Empire, the city suffered greatly at the hands of the Visigoths, the Franks, the Arabs, the Vikings, and the Normans. The citizens had to defend themselves against constant raids, so divine help was always welcome. The Basilica of Saint Severinus was built at the beginning of the 11th century, but a church had occupied the site almost six centuries earlier. There is evidence that the older church was built upon a Christian necropolis going back to the 4th century CE. According to a story preserved by the Gallo-Roman historian Gregory of Tours, bishop Amandus of Bordeaux had a dream in which the Lord asked him to go looking for a man called Severinus. Severinus had also heard a voice instructing him to travel to Bordeaux. The two men greeted each other, prayed together, and kissed. Soon, Severinus became the bishop of Bordeaux and performed many miracles.