I think it looks darn good. The only things that I would suggest are maybe put a door and some steps outside the entry (decorative and optional), the grass is a bit repetitive so break that up with a layer of clouds set to overlay, or something to break it up like a path or some bushes (again decorative and optional), and lastly the stones should follow the curve of the building but you'll learn how to do that as you learn more. All in all, nice job, man. I'd certainly hate to walk into a tower and the first room is a sacrificial room. I will wait for the next floor and see what you do with that.