Your bridge idea, I really like your theme for this one. Mine was an exaggerated comic ish looking one. For your shadows overall I would suggest having them much darker. It's hard to see them, but hopefully you have your shadows in a separated layer and you can just adjust the levels and all that. Easy fix. But for gradients, I would say that for those supports above the door could go light shadow, then darker as you approach the inward corners of them then go a dark medium for the above part, if you get what I mean lol. I don't know the proper name of those supports. Other than that, I'm really liking your bridge. Out of curiosity, how long would you say you worked on this?