You probably shouldn't do it, cause it'll kill your render time, but when a castle had a moat, the moat usually encouraged plants and moss and bushes and such to grow around it. The water you know. I might put another mountain, a bit smoother and darker behind the castle. The flags tend to lead the viewers eye out of the picture, and it needs something to lead it back around. I don't blame you if you just leave it at this tho. Render times get to be nasty. All in all it looks good. The second best castle I've ever seen, and the first best was made by a professional model maker, so it ain't too dang shabby.

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