The Lost City is a low-level adventure, in which the only hope of the PCs' survival can be found in a ruined city slowly rising out of the sands. The adventure is set inside a huge step pyramid, with the lower pyramid only sketched out and the city itself described with a list of the major areas and a map. The adventure’s main villain is Zargon, a giant one-eyed monster and his minions. The entire double pyramid, not including the city, contains over 100 rooms.
The module is designed to give novice Dungeon Masters experience fleshing out adventures and is only partially complete. Later TSR material hints that this adventure possibly takes place in Mystara, but the material is largely setting-neutral.
TSR #9049, from 1982
(this adventure can also be found, although abridged, in the anthology B1-9 "In Search of Adventure" - TSR #9190)
This adventure doesn't have any pending change requests.