From the World Heritage inscription:
When Emmanuel-Philibert, Duke of Savoy, moved his capital to Turin in 1562, he began a vast series of building projects (continued by his successors) to demonstrate the power of the ruling house. This outstanding complex of buildings, designed and embellished by the leading architects and artists of the time, radiates out into the surrounding countryside from the Royal Palace in the ‘Command Area’ of Turin to include many country residences and hunting lodges.
Italy has more World Heritage sites than any other county. It seems as if every city in Italy has one and Turin is no exception. There are many palaces around and in Turn built by the Duke of Savoy. A quick walk to the center of town will let you see several of them.