"Bottle City is a site of high adventure, where strange magic interweaves with nine trapped gods, demigods, and demons who vie for its control -- but all are minikins, captive in the magical city in the bottle!"
-From Publisher's Website
The Original Bottle City module is an updated version of an adventure that Robert J. Kuntz ran for Gary Gygax and others in 1974. The Bottle City was a "sublevel" found within Castle Greyhawk, similar to the Dungeonland module, and is thus an integral part of D&D history.