I can think of no better dungeon than an endless library.
The Black Spire Pact
Two legendary artists, one head-to-head infernal adventure.
TSR Jam 1999 (1999)
Not a game jam at all.
The Gates of Firestorm Peak (1996)
First appearance of the Far Realm. Goopy!
Labyrinth of Madness (1995)
Intentionally designed to be the most difficult dungeon ever, and largely succeeds in more ways than one.
The Dancing Hut of Baba Yaga (1995)
A tour of Baba Yaga’s chicken-legged house.
The Lost Shrine of Bundushatur (1998)
Tiny skeletons!
Abattoir Hymnal
Yes, meat sorcery!