Ok everything I read is that Medieval Castles had clockwise rising stairs in the turrets for defensive reasons. Most people are right handed like in this game and you want the attacker with his right hand on the inside curve. This prevents him from swinging his sword. The defender can swing away and is partly protected by the curve. So I needed one .. I wanted to share. It is a little fast and has no outside wall you can do that and if you want to expand the width of the stairs you can without taking out the walls. It is all wood construction with stone texture.
It blueprint extends very easily aligning the center column and any stair.. I have this in one of my turrets now with several extensions for a very high turret.
The picture is a quick experiment. I dont think it will remain with those walls. They look good inside but outside they are not so good. I left the experimental walls off the blueprint
Enjoy..