Nice work, Landorl. Hmmm - There's something odd going on with your castle shadows. I'm sure it's mathematical - something about adding instead of multiplying, or vice versa... it's like the towers and walls cast separate shadows, and the intersection is darker, as if two shadows were darker than one. Which would be true for a translucent shadowcaster, but those walls look like nice solid stone :-). Somebody who knows CC3 and PS would state it better than I.
By background, you mean the grass / etc? It's not bad, just needs some texture - enough variety to look a bit 3D. Like what I assume is a rock face S and W of the castle - it could use some sharpness to its texture. Zoomed in where you can see the blur easily, it loses its 'rockiness'.
I assume the dark lines around some farms are hedges? Maybe you could have them casting a bit of shadow too. They could be half as high as a farmhouse, but even just a few feet high they'd throw a hint of shade.