Has anyone here read Perdido Street Station, The Scar and The Iron Council?
They are steampunk novels set in a city, New Crobuzon, that one could use very much as inspiration in their depiction of Sigil.
If you haven't seen them, please check them out.
Yes, I've read them. They're very good.
Although New Crobuzon is more like Ribcage in many ways (like the giant ribcage overhead, the despotic government, and the portal to Hell).