Way back in the late 70s, a friend of mine and I found a D&D basic rules blue book and a dungeon map in a desk in a classroom. We kept it. The rulebook ended up lost somewhere somehow in the decades since, but I still have the map. Recently, I decided to redraw it, starting, of course, with level one, which I interpreting as a collection of buildings separated by narrow paths and narrower alleys. The original map lies under my WIP version.