Presenting the last map made for my Tajamul Islands, a dungeon crawl designed to prepare players for grander adventures on the Greyhawk mainland. The layout combines a cave system (for the actual mining) and a Dwarven stronghold with three sections.

Origin: Before the Southern Ostian Quake, this vast facility was known as the Gravenklaau Mine, a venture sponsored by the Archmage Ixtandraz (his identity before I included him in my FO article). He brought a regiment of evil dwarves here from the other side of the world, to engineer the deep halls and craft enormous metalworks. The dwarves were quick to enslave native humanoids to do the harsher labors. They even imprisoned a DeepSpawn (Monsters of Faerun), which could replenish the ranks of thralls. Over the years, the creature, Zroltozectlo, went insane from the treatment. Ironically, its cell was a safe haven when the quake smashed Gravenklaau.

Note: The chambers of the Bailey and Mine still have functioning magic tiles which radiate light. The trogloclops caves are completely dark except for Area 28.

1-5) Shield Bailey of the Grave Harpies: The splattered bird waste along the entry tunnel is an obvious sign of occupation. Although the disgusting harpies haven't figured out how to release the main gate, they can exit through a guard balcony at Area 2. The harpy queen nests in Area 4, and the controls for opening the inner gates are in Area 5. The decomposed body of a notable Graystormer Academy graduate, Forenzo the Mighty, can be found here along with his personal magic items (Egg of the Portal Drake, Maccad's Charring Darts, Staff of Illusion Detection).
6-7) Staircase in the Fungal Farm: Past the inner gates is an enormous cavern, layered in cart-sized fungi along the floor. A stepped bridge crosses the area, descending to an exit after a sharp turn. All the growths below are harmless, and were once a source of food. However, a large Phycomid Fungus grows across the path at Area 6. It will spray anything that disturbs it. If characters search the northeast corner of the forest, they will discover a secret entrance into Area 11. The northern edge has collapsed into an underground lake, roughly 40 feet below.
8-11) Hook Horror Chambers: A family of these beasts roams this section of the dungeon. The Horrors are angry that the fungi can attack them now, which spoils their routine of feeding on critters in Area 7 and 18. They are trying to dismantle the stonework around the secret passage, which is too small for them to climb through. Treasure here will have belonged to the original residents.
12-17) Shattered Catacombs of the Burning Skeletons: The great Quake hit these solemn halls with tremendous force. Much of the palatial western wing sunk into the basin, while a gas explosion mangled the forge chambers. Priests here were driven to blaspheme during their hopeless final hours, and were cursed to rise as burning skeletons. These undead will explode in a fiery blast when killed.
18) Underground Basin: Once a lovely pool fed by a quiet waterfall, this area became a massive pit of churning water during the Quake. The waterline is 40 feet below Area 7, and 20 feet below Area 17. An outcropping in the new lake is home to Toxic Giant Toads. Precious metal coins and rough gems can be found along the dark bottom, in the deepest fissures.
19-20) Destroyed Forge: The furnace here was once linked to a source of gas vapor, which blasted this area with incredible heat when it “uncorked”. Pieces of metal are fused to every blackened surface, and rubble appears to have smashed anything that survived the initial flare. In Area 20 is an enormous steel full-face helmet, probably meant for a colossus at least 50 ft tall. This dented relic would be valuable to metalsmiths, or a certain individual interested in the legacy of Ixtandraz.