The third level of Yliakum is known as either Stronghold or The Forge. Below it lies Land's End on the fifth level.
This is where most of the heavy industry is. Keeping the upper levels free of smog is important, so most of the industry is located by the wall, making use of huge natural vents; all smoke is funneled into them. All large scale forging is done here, such as parts for the bronze doors, sewers, and winches.