Underground Shrine Map

While trying to work out some tech-related frustrations (Photoshop + Wacom tablet does not always do what I will it to), I spent a little time today doodling by hand. Inspired by Dyson of A Character For Every Game, I drew a dungeon map on an index card, making it up as I went. Mostly I did it because I wanted to mimic his crosshatching style, which, for whatever reason, seems to give his maps an extra visual punch that I really like. I was using a .5mm rolling ball pen on a single index card instead of a .7mm gel pen in a moleskin like he uses, so it doesn't have the same smooth, dark quality his maps have. I prefer .5 for pretty much everything else, so I may have to snag a .7 somewhere just for this purpose, and draw on top of a few layers of paper.

This reminded me of another artist's game maps that I've attempted to emulate in the past to mixed results. In the WFRP 1st Edition book Death's Dark Shadow, Ian Cooke had a cool way of representing forests in his maps. Here's a snippet from one of them:

I started doodling another map, using a technique similar to this to represent the earth and stone areas outside the dungeon walls. I'll have to scan it and post it here when I finish, since I think the concept I eventually emerged with was kind of fun. It's not done yet, though, so it'll have to wait until next time.

Anyway, regarding this map: as I drew it out, it seemed to me that it was probably an underground shrine, either someplace that had been built on top of by folks who weren't too particular about preserving it, or perhaps deliberately hidden from surface detection by the worshipers who frequented it. As you can see from the old map symbols (at least, the ones included in Mentzer Red Box Basic D&D), the entrance is through a trap door in the ceiling of the domed shrine; presumably one uses a rope ladder or some similar contrivance to descend into it.

One alternate possibility is that the chamber is entered via a magical mirror held by one of the statues in the alcoves there...

What is that rough-hewn secret chamber for? Was that created by someone other than the shrine's architects?

What caused the doorway to cave in? What was originally behind that door?

What's the deal with the well that features a submerged [further] subterranean passage to the pool in the secret chamber? Is it some sort of trick where a con-man puts on a costume of some sort (kept in the chests), swims through the passage and emerges from the well into a dimly-lit chamber filled with hallucinogenic incense? Is that part of the initiation of acolytes? Or is it an escape route, should the shrine be invaded by the authorities? Or is the passage sloped so that coin offerings dropped into the well end up in the pool, to be collected by the priest later and gathered up into the chests?

I dunno - you figure it out.