This is probably one of the most impressive of the Lego sculptures and I think that the attention paid to the architecture is very indicative as to how much effort goes into recreating these things. This recreation of Neuschwanstein is something that I wish I could buy.
What you see above is very close to what Bob Carney did last year for Brickworld. Check out the spread of photos that detail how Carney was able to make this castle. I don't know if the models are the same, or if they're based on one another, but the whole thing is very impressive.