Marseille

Marseille needs 2 days: touring the MuCEM, the museum of Mediterranean civilizations connected to Fort Saint-Jean by a suspended footbridge, on one, and sailing to Château d'If, the island prison-fortress off the harbor that inspired Alexandre Dumas's The Count of Monte Cristo, on the other. May-June and September bring the mildest weather, avoiding the extreme summer heat and the harsher winter mistral wind. It's cheaper than Paris or Nice. It's France's oldest port, founded by Greek Phocaeans 2,600 years ago, and its Vieux-Port remains an active fishing harbor right in the center of the country's second most populous city.