Ruins of the Undercity is a solo adventure generator for Labyrinth Lord and the Advanced Edition Companion. The tables will generate a vast underground complex under a major city, including monsters, traps, magical effects, and treasures.

Inspired by the random dungeon creator in the original Dungeon Masters Guide, Word Mill's Mythic adventure creator, Expeditious Retreat Press's Unbound Adventures supplement, and Faster Monkey's Lesserton and Mor.