One of the best examples of military architecture, the 17th century Besancon Citadel is located in Eastern France. Constructed by the Spanish for defensive reasons, today it's home to several museums and is one of the country's most visited castles.
The UNESCO site has a museum devoted to deportation and the French Resistance during WW II, as well as an archaeological museum. Children enjoy the children's farm, and the castle also houses a museum of natural history, as well as a restaurant.
Aside from the several museums, it's worth visiting for the views over the surrounding mountains and the nearby city of Besancon.
