France's oldest city rises from its old port in layers of salt, stone and swagger — and it plays to win. This app-led scavenger hunt takes you through Marseille on foot, using phone-based riddles to guide you from one landmark to the next. No guide, no fixed start time. • Start by the Hôtel de Ville, survivor of the old port's dramas • Climb toward Sainte-Marie-Majeure, the striped giant by the sea • Trace the ramparts of Fort Saint-Jean,...