Definitely the first option, there are so many cool things that could be done with it, some of which I mentioned in my reply had was timed events in the world where some structures are only avaliable to access at the right time and place, with information spread around in the world that tells you where and when it happens, so you might backtrack to a tower you went to very early on because something floating gets real close to it at a certain time, which you only learned about long after doing the tower.