stone textures are a little dull and lack character. Think about how the environment, even on something new, would effect it.
Also, its a little fractor-ish. Looks a bit procedural.
What environment is it in? Would snow and water run off effect it in areas where that might happen. Was there ever a fire or fires out by the walls where smoke might effect it? Is there vegetation that might inspire mold or grows on area of the bricks effected by moisture? Or is it a dry desert where sun might bleach areas? Anything that might happen to make suttle changes to the texture will take it to the next level. Things to think about. Don't age it just to do it, think about how real things work. Were parts of your castle build earlier than others? How long did it take to make the spires after the foundation was laid? If its 50 years or so, would those first sections look a little different in tone?
All those things when creating models and textures should be thought about these days now that we have the ability.
Just stuff to think about ![]()
otherwise, I really like the design, I wouldn't want to attack it.