What I remember is a dungeon crawl sort of module laid out as an inverted pyramid. There was art that depicted the builders vision of the souls travel to the afterlife.
At the apex of the pyramid, was the lair of the "boss monster". The art at the apex was supposed to depict the final step of the souls journey; but it has been defaced.
This would have been the early 80's, so AD&D 1e most likely. We were kids, it's definitely a possibility that this was an unlicensed module of some sort.