https://i.redd.it/orxo9v353zmd1.jpeg

This project is called the Stygian City and you can find usable maps for the dungeon here. All of this was hand-drawn on paper. You can see the original drawings here: (pic, pic, pic)

Here's an overview of the Stygian City. Only the first 12 levels are done:

1-2: The village

3: Villagers' mines

4: A maze of tunnels and collapsed chambers overrun by mold

5: Caverns inhabited by giant bats

6: Catacombs

7: Goblin village

8: Giant spiders, huge webs strung across the pit

9: Ancient temple

10: Industrial workshops

11: Hag's thralls

12: Night Hag's palace

To do:

13: Kuo-toa settlement and river

14: Main kuo-toa settlement

15: Bridge across pit between kuo-toa and myconids

16: Myconid colony around a crumbling fountain

17: Ancient oracle and library with a long-abandoned scholars' camp containing notes about the pit's history

18: Undead/Demons. Magic Stuff?

19: Ancient prison

20: Ceremonial jumping point with temple

21: The bottom: Ghanya (with several variants of the bottom level, including a sealed vault/prison, underdark entrance, trash and debris and aboleth lair).

You can read an overview of the lore here. There's more detailed lore in the DM notes for supporters of my patreon as well if you're interested.

I draw a lot of big projects like this and, if you want to see the rest, you can find them all on this page.