The railway links the large cities and smaller historic centres along this Atlantic-to-Mediterranean corridor. Bordeaux opens with a broad riverfront and wine-trading streets; Toulouse brings warm brick, medieval churches and a day devoted to space exploration. Carcassonne changes the scale with its upper fortified Cité and the lower Bastide beside the Aude. Narbonne then offers a compact market-and-canal stop before Montpellier’s narrow lanes and royal promenade. May, June and September are good choices for a trip built around walking, outdoor views and substantial indoor visits. July and August are workable, with earlier walks and longer lunch breaks. Two one-night stays at the end make the rhythm more active, so this route suits travellers happy to move their own luggage. The three-night Toulouse stay supplies the longest pause and two complete sightseeing days between rail transfers.