threw together a quick perspective reference for you to analyze and compare your current lines. Im assuming a 3 point perspective piece given the viewing angle youve already established (plus they look really neat for structural stuff). Notice that the perspective lines in red angle the opposite way that you currently have illustrated. As it currently stands, your structure's perspective is indicating a topdown viewpoint, while your ground indicates an upward, worm's eye view.
the way i see it, if you pull back the walls to go a good bit 'deeper' into the horizon, you can get a much more expansive illusion of distance. if you want that 'towering over you' angle shot, you could pull down the origin points defining the grey lines so that the foremost tower looks quite tall as if you were an ant. but to be honest i think the angle youre inferring now should do just fine. (note you could also just make the towers vertically taller).
I think what youre having a hangup on is how to push the details of the illustration, not how to render it. Studying existing architecture that fits in the style of what youre trying to convey and adapting that into your work should help steer it to where you want to take it. Just remember though that the details should fall into sync with the perspective or else the entire illusion is lost.
i just started randomly scribbling some color into it and did some sad gestural attempts at other stuff behind the wall to help give it some depth. notice the color will taper off to a cooler atmospheric blue and that should help sell the depth (i neglected to do this for the ground as well, but the same theory should apply.)
anyway dont be afraid to be a bit messy with your initial work, sometimes that can lead to unexpected positive 'groups' of pixels that work really well and feel more natural than if you were to have planned it all out with the line tool.
i hope that youve found some value of this.
EDIT: - ive taken note that you were hoping to go the whole burnt to hell under ominous atmosphere route - in which case i may have to inform you you may wish to reconsider your current hue choices to convey that, and also makes my color scribble of a perfect blue sky day at the beach largely irrelevant, haha.