There are some extraordinary places to stay in France including hotels within fortified castles such as:-

Chateau Fort de Sedan (08 Ardennes, Grand Est) is a unique medieval fortress and is the largest in Europe (35,000 square metres) open to the public all year round. The Hôtel Le Château Fort is within the walls of the castle, yet has modern accommodation and  facilities. There is also an annual medieval Festival within the walls of the castle!

For more info and to check availability on the Sedan Château Fort Hotel

At Blaye (33 Gironde, Nouvelle Aquitaine) there is a hotel within the Vauban Citadelle – Logis Hotel de la Citadelle. Within the town of Blaye and with views across the River Garonne to the Medoc. (there is also a ferry across the river (vehicle and pedestrian). There is a wine festival  within the walls of the Citadelle where local winemakers offer tastings of their wines.

For more info on this Blaye Citadelle Hotel see Logis Hotel de la Citadelle