Once a port, Montreuil-sur-Mer is now stranded 13km inland, after the River Canche silted up in the sixteenth century. Perched on a hilltop above the river and surrounded by ancient walls, it’s compact and easily walkable, with fine views from its hilltop ramparts. Laurence Sterne spent a night here on his Sentimental Journey, and it is the scene of much of the action in Victor Hugo’s Les Misérables, best evoked by the steep cobbled street of Cavée St-Firmin, first left after the Porte de Boulogne.
Two heavily damaged Gothic churches grace the main square: the church of St-Saulve and a tiny wood-panelled chapelle tucked into the side of the red-brick hospital. To the south cobbled lanes are lined with little artisan houses. In the northwestern corner of the walls lies Vauban’s Citadelle, ruined and overgrown, with subterranean gun emplacements and a fourteenth-century tower that records the coats of arms of the French noblemen killed at Agincourt. Don’t miss the World War I exhibition in the vaulted underground rooms of the tower.