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