Hey Xefline,
This turned out really great! There are still a couple of perspective issues and I think that is probably what is bothering you. The stairs and the interior of the keep seem to have a totally different perspective than the exterior. The steps should be following the same perspective as the other major horizontal lines going down towards the vanishing point on the lower right side. The inside of the keep is also implying that the horizon line is somewhere in the middle of the canvas since we can see the floor on top of the steps as though we were looking down at it while the rest of the image implies that the horizon is somewhere below the bottom of the canvas.
I don't really know if i'm explaining this very well so I made a little diagram that will hopefully do a better job.

I hope this helps and makes some amount of sense...