The Musee des Docks Romains preserves archaeological remains from the ancient warehouses around Marseille's old harbour. Large storage jars, foundations, and finds from the Phoenician and Roman port help explain the city's role as one of the Mediterranean's old trading centres.
It is a compact museum, best treated as part of a walk through the Vieux-Port and Le Panier rather than as a standalone half-day visit. Check opening status before going.