The Tunnels of Mega Burg can be broadly divided into two dominant areas, the Lower and Upper Tunnels. The division between the two came from not only closeness to the surface but also natural light access during the day. Those living in the Upper Tunnels scoffed at those living in the damper, darker Lower Tunnels, even though it was the Lower Tunnels that had easiest access to the sewers.
Initially most rats settled in the Upper Tunnels, and those who could chose to remain there. As the colony grew however rats ventured deeper, and deeper underground.
Even though all of the rats were exactly the same it was considered a privilege to live closer to the surface, while those down on their luck lived in the deepest tunnels.
This social and eventually economic division led to strife and in-fighting between the dwellers of the Upper and Lower Tunnels. Even though some have tried to resolve this division, to try and make the colony equally habitable for all, it could never truly be achieved.
The Lower Tunnels also considered themselves, often, free from those controlling the Upper Tunnels, such as the Protectors. Even though life was at times difficult it was the strongest who survived in the Lower Tunnels.
As such one could say the following about each of the tunnel sections:
The Upper Tunnels were under stricter colony control, and either the first rats lived there, or those related to them, or those who could in some manner force their way there. They never suffered shortages of food, being close to the common den where most fresh food was brought in, and under constant protection of the Protectors. Only certain types of businesses could be found here, and usually those rats with very specific or distinct tastes could would be welcome here.
Meanwhile the Lower Tunnels were the „land of the free”. One could do as he pleased or wished, as long as he had the food to do so, strength or influence. It is also here where one can find many seedier groups or gangs of rats. Anything is possible in the Lower Tunnels.
Those tunnels that were the meeting point of the Lower and Upper Tunnels never had a formal name, though they could be considered the Middle Tunnels. Due to relative proximity to the sewers and the surface it was in the Middle Tunnels where one could find the majority of maker workshops and seeker shops. The commercial heart of the colony.