Christ Church College in Oxford is a working college with students studying and living. The tour of the college is probably my favorite in Oxford! It includes a self-guided audio tour. This is also where you will see THE FAMOUS HARRY POTTER STAIRCASE! You can walk up the stairs and into the dining hall, just be sure you don't come during the student's lunch time as the dining hall will be closed (check online for the time, but it's typically 12 pm - 2pm).