Amherst Stockade Board
Hidden beneath the secluded forest village of Amherst, these skull-littered tunnels have served as temple, arcane laboratory and dungeon for the lords of Amherst in their mad quest for immortality. The party, having arrived in the village as guests of honor for a mysterious festival, found themselves trapped in the cells with what remained of generations of failed experiments.
A big dungeon, with multiple exits/entrances. Certain walls are meant as secret doors, and you can hide areas with hide volumes to make them less obvious. The walls are pretty easy to replace with normal doors, if you so choose.