I'm not sure if this is meant to be a defensive castle (fortress) or a Palace but the space in the center is overly empty, it feels like there should be another structure there, possibly taller than the towers surrounding it.
My avatar is Captain Casval Ren Deikun aka Char Anzable, the Red Comet, Lieutenant Quattro Bageena, Edouard Mass.
he is the Best MS Pilot, capable of using something bad and taking on a Gundam, only being let down by it's bad weapons. he is amazing all round really. popular with the ladies too. the avatar is of him when he is being Lieutenant Quattro Bajeena.
previouly it was my old RJS Thunderer build, proper battleship, fictional and of my creation.
The Meaning of Life, the Universe, and Everything.
Do not be afraid of breaking symmetry. vary the hight and shapes of the towers. and try to think objectively. What is the castle for? a fortress of defence? or a royal palace? if defence is what you are wanting. i would suggest doing some google image searches on castle keeps and fortresses.