Still getting my head around a different kind of megadungeon design for the endless stair; something that appeals to my naturalistic adventure design aesthetic.
This is a map of St. Paul's catacombs in Rabat, Malta. That catacomb map would have made for an inspirational reference for Death Frost Doom, a James Raggi adventure full of menace and horror but lacking in evocative cartography.
I continue to be attracted to maps and images like this one of St. Paul's catacombs. As an adventure designer, there is an honesty in using real world subterranea for the basis of one's own maps, if only for the designer's own moral fortification.
The user of the adventure may not appreciate that the environment does, and therefore can, exist. But from the creator's point of view, there is a certain amount of satisfaction in knowing that the environment makes sense.
What's most challenging for me is attempting to visualize these catacombs. There are a handful of images on the internet, but I think it would take actual exploration of an environment like St. Paul's catacombs to truly appreciate the depicted map. The next challenge would be to communicate what you have seen to the end-user of the adventure in a way that is not burdensome.