Undercity
this was the name used to describe the lowest levels of the immense city-pyramid that dominated the habitable landmass of the planet Aargau. Beginning at Level Seven, the Undercity was accessible only by a few known entrances. A wealth of illicit and clandestine passages were established, lost, and rebuilt over the centuries, allowing all manner of beings to reach the level. Much of the Undercity was set aside for criminal activities, and black-market moneychangers were especially plentiful, garnering a profit from those beings who didn't want to deal with the Aargau banking authorities.