I have always wanted the original 4757 Hogwarts Castle because it had a clock and a pendulum! I found its clock works to be a GREAT mystery until I could look into its instruction manual!  Lego was so gracious to create the new Clock Tower and release it! I loved it very much. However, a great feature was missing: the pendulum! I decided to make minimal modifications for adding a pendulum and even motorizing it! My Clock Tower's clock work would not be a GREAT mystery because I made a video which showed how I built it!