Prompt: the last city, all of humanity stacked on top of each other in an endless scramble. The edge of the city is an abrupt cliff-like wall of haphazardly stacked ramshakle dwellings, which shifts from time to time to keep up with the strain of its own weight. Beyond that is nothing but fetid marshes. Above it all, columns of steel and stone rise over the scattered tenements: ancient spires of terrible majesty dominating the urban landscape, between them narrow catwalks and tangled wires bridge dark chasms. A dim haze and dirty grime permeates all. Great forges glow and wires crackle with energy.