Of course! The old Québec city is a must-see! I recommand you to take a walking tour. I am myself an official tour guide but if I am not available, contact Tour Voir Québec (a company I work for).
If you like driving or would like to take a tour, don't miss visiting Old Quebec city! Beautiful part of the history of Quebec, great for shopping, food, drinks and taking pictures.
Take the stairs or the elevator at the end (or beginning) of De la Couronne street and turn left. You will find the Old town just after the Honoré-Mercier boulevard.