This small town/village is fairly large for underground, (as is the cavern). There are three large buildings and about two dozen smaller buildings. The smaller building looks as if they are houses, maybe two rooms with a loft. (It's hard to tell from the ledge). One of the large buildings looks to be a shop, for people who seem to be leaving with goods when they hadn't any going in. This building is close to one of the exits on the opposite side of the cavern from the ledge. Another of the three large buildings is in the center of the town and perhaps is a meeting hall, for few seem to be going in or out of it at the moment. And the last larger building looks to be a tavern, and is situated near the "meeting hall".
The ledge the party is on does lead down to the city, which is well lit with the magical crystals. The town is bustling, as are the small mushroom fields on the edges of the cavern.
The longer the party sits and stares at the town the more likely they will be noticed. (10% chance each "round", that they will be noticed.)