Re: Hey, what's in those ruins?
I don't know how your game's theology works, but if cities have patron gods, maybe those of this city are still around somewhere beneath the ruins, but weakened and driven mad from lack of worshippers, time and loneliness. Maybe they've been built up some kind of erzats cult based on whatever goblinoids/rat people/four-eyed mutants live in the area, resulting in a mad perversion of the noble rites the inhabitants of the city once carried out in its prime.
(I like Lovecraft. Can you tell?)