Founded in the 4th century by St-Cassien, who sailed into Marseille full of fresh ideas on monasticism that he acquired in Palestine and Egypt, this church grew to formidable proportions. With a Romanesque design, the structure would be as much at home in the Middle East as its founder was. The crypt, St-Cassien's original, is buried under the medieval church, and in the evocative nooks and crannies you can find the 5th-century sarcophagus that allegedly holds the martyr's remains. Upstairs, a reliquary contains what's left of St-Victor, who was ground to death between millstones, probably by Romans. There's also a passage into tiny catacombs where early Christians worshipped St-Lazarus and Mary Magdalene, said to have washed ashore at Stes-Maries-de-la-Mer.