Wow, what's your map packing to fill up the brush memory that much? I'd suggest compensating area's of needless detail to even your map as a whole and put detail where it is needed elsewhere. Those windows for example, along with the inner curved watch tower walls, they are nice, but needless eyecandy that isn't complimented well by the rest of your map or its theme. You could simply have it a square-ish design with a
diagonal corner with a window model in it IE
click. It would be appropriate, wouldn't look
terrible and would probably consist of about 10% of the original brush and brush face count.
Or perhaps choose a better texture because a brick wall doesn't look right curved like that. Concrete would look less fake.
If i were to have done that yard, i would have made it sandy, doable with 1 displacement and made the path by placing planks of wood in the sand as path guides (either side of path, skewing the angles slightly and leacing a small gap between each plank so they arn't perfect-clean and monotonouse in appearence. The sandy theme has complimentary rock models at hand hand as well to litter your empty yard with.