Old Game Notebook: Anyone Recognize This Dungeon?

Just found of sheaf of maps hand drawn on graph paper and, from the other game-oriented contents of the folder, and thinking it dates from somewhere between the late '80s and early '90s. While I recognize the dungeons depicted by the other maps in the folder, however, I cannot recall anything about these two, which appear on opposites sides of the same sheet and thus would seem to be somehow related. They appear to be players' sketches, one of an apparent aboveground and the other of a dungeon area, and were evidently meant to be viewed vertically (although I have titled them horizontally to be more user-friendly here). The aboveground map appears to depict a small fort guarding the entrance to a subterranean area, which is the sort of thing I like to do, but these do not look like anything I actually designed and I can't even remember exploring them as part of someone else's game (e.g., my father's, in which case it might be from Dragon magazine). 

So does anyone recognize these maps and know what they are from? A free download of d-Infinity magazine for anyone who can point us all in the right direction!