Rusty is a kobold from deep in the Underdark. While actually from a little village called Ring's Hollow -- so named for silver translucent mushroom rings that grow in the area -- he often visited the nearby "big city" growing up. The city was called Iskternesj or "Star Stone" in draconic, named for the glittering mineral that made up the whole space, like sparkling starlight in the void.
Towering spires of the curving, otherworldly black mineral arch and bend, creaking and whistling as dry winds from deep in the cavernous pit send gusts of cold air spiraling through. Homes and businesses are carved into the rocks, glowing from within with soft golden light -- although most prefer to remain in darkness, learning to ply their trade by touch and memory rather than sight. Treacherous rope bridges cross over the spires where kobolds leap and scamper in the shadows.
In the center of the city, a sheer cliff-face stands, only a single narrow staircase carved into the ancient rock, crumbling and in ruins, leads to the very top. There, a great shadow dragon sits, idly swishing his tail and watching the citizens travel about their little lives. Rarely does he come down, barking orders from above for new conquests, new territory, more, more, more. His red eyes always watching. Always.