Gotta say, having been unforgivably sniffy about the computer rendering, the end product looks very nice.
The detail looks slightly shallow, but hell - it's better than MDF. It is, of course, also ever so perfectly cylindrical, whereas real castles always manage to look a little bit higgeldy-piggledy and organic somehow. But overall, it looks great.
Sorely tempted, but will probably wait to see what the rest of it looks like. Good luck with it.