You are on travel in Italy. You love wondering in the medieval centers of its art cities. You have been to Rome, Florence, Bologna etc.
Where to go?
In the middle age Italy wasn't a unified country but fragmented in many little reigns, called city-states because they were limited to the surroundings of each city ruled by the most powerful noble family in town.
The heritage of that era are a lot of little cities, located above all in central Italy, where you can spend a nice day-trip "within the walls", between a castle and a cathedral, in winter as in summer.