Imho there are too many places to visit in Italy, expecially if you like art and history Which part of Italy are you going to stay in?
Well, I think you'll visit all the most important and famous city, like Rome, Naples, Florence, Venice and so on. A place, that isn't always visited, but IMO is wonderful, is Umbria: many little medieval towns on the top of the hills, I went in Assisi lat year and I loved it. If you like the sea, southern Italy has a lot of places..maybe I'll go to see Puglia, to visit Castel del Monte and see trulli, a traditional type of habitation. These are only two place where I'd go, but I could speak about my country for hours (forgive my mistakes, I can't speak english very well )