Rouen

This port on the Seine was an important city through the Middle Ages. Among its sights: hundreds of medieval half-timbered houses, a remnant of the castle where Joan of Arc was tried for heresy and the Gros Horloge (Great Clock), housed in a 14th-century Gothic belfry. The clock kept time for five million hours without stopping once. The embalmed heart of Richard the Lionheart was buried (and later exhumed) in the city's Cathedral of Notre-Dame, also called Rouen Cathedral.