With only one night, I expect to try and see the Roman forum architecture and the cathedral, have a nice meal, and rather little else. What else is ab absolute must-do (or must-eat) on a short visit?
bumping this up... also to add -- We will be there on a Monday, so many museums may be closed. Worth a visit anyway?
I'm haven't responded as yet because I was so disappointed by the near centre city - envision rust belt then multiply by 10 -, really really abandoned and awful, that I didn't go into centro storico.
I know that the town has a shopping centre and does outlet stuff, and that the Mille Miglia starts there - in fact starts this weekend.
I hope you have a better experience than me.