Ghouls do not build. They are parasites and scavengers, eaters of carrion. The city they call Ghûlheim is something they found, long ago, but did not make. No one they call knows (if anyone human ever knew) what kind of creatures it was that made those buildings, who honeycombed the rock with tunnels and towers, but it is certain that no-one but the ghoul-folk could have wanted to stay there, or even to approach that place.
Even from the path below Ghûlheim, even from miles away, Bod could see that all of the angles were wrong — that the walls sloped crazily, that it was every nightmare he had ever endured made into a place, like a huge mouth of jutting teeth. It was a city that had been built just to be abandoned, in which all the fears and madnesses and revulsions of the creatures who built it were made into stone. The ghoul folk had found it and delighted in it and called it home.
A dark and disjointed scent: smoke and black musk, bladderwrack, opopponax, galangal, and pepper.