Under the City

From the publishers blurb:

Few suspect the depths of danger, depravity, and adventure that can be found Under the City. In this six-page, six-level mini-mega-dungeon you'll find:

Maggot-men, sewer gators, oozefolk, basilisk cultists, street gangs, psychic toads, and more
Dozens of rumours to draw in gold-hungry adventurers
Multiple interlinking factions and threats
Unique content that can nonetheless be easily embedded in most fantasy settings
Challenges fit for low-level parties, with a few surprises for even more experienced groups