When you live at the bottom, the only thing you have is to look up. If you're lucky you can see the lights of the great towers and the stars. If you're like most people, you just look at concrete. But the stars and lights are still up there.
These well crafted Dwarventi stairs lead down into one of the three main passages of Undertown. The underfolk have cleverly made it look like a short surface streets. Some of the branching passages look like streets as well, but it is all just a facade, soon they become more mine or hall like. The streets are “lit” (dimly by any topsider’s opinion) by mage lights and a few ancient amber Dwarventi Lights.
For all the aquaducts coming into the city, there munt be a place for the water to leave. Thus, many years ago, the Blackwater Tunnels were commissioned to carry sewage away from the city buildings.
I was in a game with a GM that had a Masters in History, who made is a point to mention that the local peasants didn't have wheelbarrows. The rest of the players just shrugged that off but I knew that the GM was trying to tell us the peasants were on the knife edge of starvation.
All that from wheelbarrows? Yes, because before the invention of the wheelbarrow it took two men to carry that load. In it's time the wheelbarrow was the most explosive production multiplier that the peasantry could get their hands on.
This is worth two tips: One about the power of the Wheelbarrow and the other is the moral of the story...that people need to know the point you are trying to make.