I came across the following map at the 'Tower of the Archmage' blog. I don't really know what this is about apart from assuming that it is a game of some sort. What interests me is the way in which the map is made using squared paper. This is the first Megadungeon map. The name perhaps gives a clue as to what 'Tower of the Archmage' may be about.
Further maps - and how they fit together - can be found on the Megadungeon Maps - 1st big level page. (There is also a map label with numerous entries to click.)
Using a book of squared paper, a 3D map - or at least a map with numerous levels or layers, one per page - can be produced. It could even form some sort of 3D maze.