The Fenestrelle Fortress, better known as the Fenestrelle Fort is a fortress overlooking Fenestrelle. It is the symbol of the Metropolitan City of Turin, Piedmont, northern Italy. It is the biggest alpine fortification in Europe, having a surface area of 1,300,000 m². The fortress, built by Savoy between 1728 and 1850 under the design of the architect Ignazio Bertola, guards the access to Turin via the Chisone valley and stands at altitudes between 1,100 and 1,800 m. The territory was acquired in 1709 by the Duchy of Savoy after the defeat of the French at Fort Mutin (Fenestrelle).