Belfort lies just the north of the Jura Mountains and the south-east of the Vosges Mountains, controlling the “Gateway of Burgundy”, a natural route between Alsace and Franche-Comte. The old fortified city lies between the River Savoureuse and the bottom of a cliff at whose summit lies the chateau.
Belfort belonged to the Austrian Habsburgs from 1360 to 1636 when the city was taken over by Gaspard de Champagne, Count de la Suze, on behalf of Louis XIII, king of France. Gaspard de Champagne repaired the old city walls and improved the chateau.
Between 1637 and 1648, he added a crownwork with one demi-lune to modernise the chateau’s defences. The city was confirmed as a French possession under the authority of the king of France by the Treaty of Westphalia in 1648.