I did the block-in modeling for the rock walls and set up our camera and set dressing to match the reference image.
I uzed zBrush to subdivide and sculpt in detail in the center formation and and left wall. I touched up Josh's sculpting by adding a door to better match the concept art. 


I lit iteratively, making small adjustments.
Our materials were a mix of maps and procedural textures, with the stone having procedural bump augmented by normal and AO maps. The steel plates had textures painted by Josh.
This is our mentalray render:
I did our compositing work in AfterEffects. I color corrected to better match our reference.
We had zdepth renders that I used to create depth of field.