In Refinery City, everything is gigantic, all the proportions are much larger than anything that would be conceivable in the waking world. The walls really are half a mile high, made of blood red iron, and must be miles in circumference, they dwarf the figures at their base. A moat of boiling blood surrounds the circular city, a half mile wide, writhing and frothing and letting out a sick stench. A single long causeway crosses the moat at each cardinal direction, joining the roadway to the city proper, ending in a pair of massive iron gates that are the only opening in the walls.
The steal girdered causeway is teaming with traffic, infernal engines compete with endless files of damned souls carrying various cargo into and out of the city.
Rising above the massive walls you can hundreds upon hundreds of smokestacks, massive cylinders much even taller then the impossibly tall walls. Some belch out an endless cloud of black red gasses, the tips of others burn, vomiting massive columns of fire to the heavens.
A vast network or pipes, conveyors and walkways nits the lower levels of The Stacks together in a tangled network, a city above a city. The light of the burning stacks is so bright it illuminates not only the city but provides sooty red light light to the entire realm, filling the role the sun normally plays in the waking world.
Finally, at the exact center of the metropolis a tapering column of raw stone, hundreds of yards thick vanishes up into the smoke filled sky. Like the spoke of a wheel, the entire city radiates out from this hub. You can dimly see it stretch all the way to the rock ceiling of the realm, miles above you.