Currently, bell towers are a complete pain to work with. They can be pushed/pulled, but can't be loaded... so if you want to add another floor to your bell tower building and move it up a story, you have to destroy it and create a new one instead. Unfortunately, you also can't bash them, so the best you can do is shove the old one off deed and hope for it to decay. I don't see a reason why they shouldn't be able to be loaded into carts/wagons/ships, or at the very least, bashed so you don't have to deal with extra ones lying around until they decay eight years later.