Valle d’Aosta is well-known for its medieval castles. Perhaps the most famous is Fènis Castle, one of the most important examples of 14th and 15th-century military and civilian architecture. But also, Issogne manor-house , Verres Castle, Sarre Castle (the Italian royal family residence when they came to the valley) and Saint-Pierre Castle, which hosts the regional Museum of Natural Sciences. 

Bard Fort is also interesting, an imposing construction built up above the ancient medieval village and guarding entry to the Valle d'Aosta. Following significant renovation works the fort was opened to the public in 2006. The fort hosts the Alpine Museum, also including a children's section, interesting temporary exhibitions and other events.