The first 3 shots look very good, but in the 4th one I think you went a bit overboard with those funky, brush made column/support structures. It looks like you added them for cosmetics but they rather hurt the look, because they are not only made of brushes but look poorly built too. I would get rid of them completely and use the freed ressources to spend detail on the rest of that fortress front. Some texture variation also wouldn't hurt there, too much concrete..
Just my 2 cents..and as I said - rest looks really good! ![]()