Carcassonne

Carcassonne needs 1 day: touring the Cité de Carcassonne, Europe's largest fortified medieval citadel, with a 3 km double wall and 52 towers restored in the 19th century, in a single visit. April-June and September-October bring the mildest weather. It's inexpensive for France. Its restoration, led by architect Eugène Viollet-le-Duc starting in 1853 after centuries of neglect, is considered a pioneering case of modern heritage conservation, and the citadel has been a UNESCO World Heritage Site since 1997.