There is one large main entrance to the dwarven catacombs (also referred to as 'belowground'). A paved road goes through a wide cave mouth to the Grand Cavern, festooned with sparkling stalactites and filled with dwarves, gnomes, and a few other races going to and fro. Despite its size, the Grand Cavern is magically well-lit. Its walls are lined with shops and residences. Numerous darker passages lead off of the cavern to dwarven farms, markets, mines, temples, and residential areas. An especially large passage leads to The Arena.
The belowground residential areas are known as 'towns'. The three largest are Clifftown, which is east of the Grand Cavern; Undertown, which is north of it and deep within the mountain, and is the largest dwarven community; and Mushroomtown, which is west of the Grand Cavern and near the subterranean fungus farms. Routes to the Mines issue from these three towns as well.
There are several smaller connections between 'aboveground' and 'belowground', but they are not as widely used as the entrance to the Grand Cavern. There is a large passage connecting Clifftown to the aboveground community of Northville. Underground connections to the outside world might exist, but if so, they are long and difficult, and are only known to particularly adventurous (and secretive) dwarves.
Mining still continues in the catacombs, with tunnels constantly being constructed or sealed away. Fortunately, dangerous underground animals are rare (as long as one does not delve too deeply).
All Enclave citizens are welcome in the catacombs, but only dwarves and gnomes tend to venture deep into them, aided by their darkvision and low-light vision. Some smaller-than-average half-orcs live in the catacombs. A few humans and halflings live in the Grand Cavern, Clifftown, and Mushroomtown. Occasionally young humans or halflings attempt spelunking, get in trouble, and have to be rescued by dwarven miners or rangers.