I agree about the straightening, and that made me think that the whole 'verticality' problem seems to be caused by lens distortion; I tend to believe this can be exploited even further; the curves are already winding and all in all I really love the way everything gets confusing with the tower leaning towards the right and the wall towards the left for my taste, it would work even better if they were leaning even further apart. So from this point of view, I ended up loving the distortion.
However, I wonder if the contrast isn't a bit too high. (High contrast works great for b/w shots but it's so difficult to master properly...)