In the southeastern corner of Paris, Vincennes Wood encompasses some 995 hectares. It is one of the ‘lungs’ of Paris. On its northern edge, Château de Vincennes is a bona fide royal château with massive fortifications and a moat. The château grounds can be strolled for free, but the 52m-high dungeon (1369), a prison during the 17th and 18th centuries, and the Gothic Chapelle Royale (Royal Chapel) can be visited only by guided tour; call ahead for times.
