Environment Concept Design: The Caves beneath Sewers

Continuing from last week, I'm gonna be talking environments.  Admittedly, this is working a little differently than I'd like, as concept art needs regarding environments shift depending on the panel with this medium (A fancy way of saying I'm quite sure what I need and I'm making up as much  as I can as I go).  That said, the tighter your pre-production, the easier it is when you actually start working. So, here we go!

These are the caves beneath the sewers.  The prevailing idea is that either these were extensions to the sewers that were never finished, or they were pre-existing caves that the sewers just happened to connect to.  No one really knows; there's proof for both (ladders and other architecture vs. hollowed out walls). 

Design-wise, I wanted this to be really simplistic. At first it was going to be just BLACK with just the characters, but that was just a bad idea.  I need SOME sort of environment. So, instead, I'm doing just slight highlights and reflections, with just the hole as a source of light.   Enough info so that you can see everything, but not so much that you don't see how DARK its supposed to be. Hope you're not afraid of the dark and/or the horrors within! hehehehehehehehehehehehe.......