Actually, it never shows the top of the Shinra Building in DoC. That is the only part of it that Sephiroth destroyed in AC. The rest of it was left pretty badly damaged, and that's the way it remained in DoC when Vincent revisited it. It was pretty badly destroyed from VII and AC (what with Diamond WEAPON blowing up the top and then Cloud and Sephiroth having a duel there) but the building remained, for the most part, fully intact. Obviously it's going to look a bit rundown, but not much more than that.