D&D 3.0: Tales from Mystara
Old Caves: These caves were before a set of mines mined by the locals that take more than one mountain. Records show that they were abandoned for lack of viable resources.
The place was later inhabited by monsters. Goblins, skeletons, horrible creatures and even cursed ghosts are told to inhabit this place. At least rust monsters, gelatine cubes and ogres have been killed inside the caves.
Legends told of a secret batch of gold left there by a band of bandits that is hiding inside the caves behind a false wall that has a fountain nearby.