From the Introduction:
Somewhere under the city's streets, not deep enough that they can't be smelled at times but deep enough to take them off most citizens mind these sewers serve the purpose of keeping the city's wastes of its streets. The sewers were a major improvement to the quality of the citizens life. Built not by royal decree or even with the king's money but with coin from the guilds purses and by craftsmen of the guilds construction of these sewers took years. However the sewers were worth the effort. Since their completion the city has been spared the worst from various plagues that have ravaged the land.
The sewers were built from heavy stone blocks to withstand both aggressive wastes of the cities various workshops as well as the regular flood during the rainy season. Still the sewers have suffered over the years. Various mushrooms and lichen have started to grow on floors and walls, providing a little illumination, and the iron bridges spanning the channels consist mostly of rust these days.
This particular section of the sewers serves a special purpose. Here the sewage from three major tunnels is collected. Through rusty grates set into the ground the smelly tide drains into a deeper natural system of caves that takes it well out of the city. Small whirlpools for mover this grates and woe is anyone that should get caught in them. At the very center of the room a iron ladder, just as rusty as the small bridges leads up to a manhole.