The Castello Ducale is one of the Residences of the Royal House of Savoy, dating from the 12th century, originally a possession of the counts of San Martino. In the 17th century it was turned into a rich residence by count Filippo d'Agliè, but was ravaged during the French invasion of 1706. In 1765 it was acquired by Charles Emmanuel III of Savoy and sold it to his son Benedetto of Savoy who had it radically renewed ten years later, under design by Ignazio Birago di Bòrgaro. From then on it was a summer residence for the Kings of Sardinia. It was sold to the Italian state in 1939.
The Castello Ducale has a monumental façade with two stairs and a fountain; the interior includes 300 rooms, mostly provided with contemporary furniture. The castle is surrounded by large English- and Italian-style gardens.