France: Chateau de Sedan (Sedan Fortress)

Sedan Fortress is one of the largest medieval castles/fortresses in Europe, covering an area of 35k sq meters and rising 7 stories high. Located in the heart of the town of Sedan, the fortress is fortified by 5-meter thick walls all around, multiple ramparts and towers, bridges, and vertical drops. Inside the walls, are several large buildings, now housing museums and a hotel with restaurants.