Every castle needs a moat! Here is a link to one that looks pretty amazing: http://r3v3r53d.deviantart.com/art/Mine ... -256834272

Thanks for taking time to give me this information!

Cracked stone about 1/10 of the total blocks will give a very nice accent to the castle as a whole, as being a mountain castle you want a large tower above the main keep but not in the center but off to a side, spruce wood for the roofs in my opinion is your best choice maybe use some spruce fences for windows as medieval castles 99% of the time didnt have glass but wood shutters or was just wide open, for the floor generally most castles just had stone bricks dragged up and used as a floor so the stone slab block or andisite block is best choice for an authentic flooring, being in the mountain there is high moister so tossing in some mossy stone is also acceptable but have them in abotu patches of 5-10 blocks and near the bottom of the walls

thats about all i can think of right now as for what a medieval castle would look like. so good luck with the build.