Welcome to the Return of the Mammoth Dungeons.
The Dungeon Under The Mountain is a massive dungeon you can locate anywhere in your campaign world. Each level contains hundreds of rooms ready to be filled with the critters of your choice and with the devious traps you prefer.
The Dungeon Under the Mountain, Level 2
This level is less chaotic than the first one; great pillared halls and endless corridors are the main feature of this level, maybe the dwarves built it? Also, a very large chamber with a big ziggurat can be found here as well as many water-filled rooms. Three staircases lead to this level from the first one, and some dark stairways lead to the next, deeper level.