Huh. I was going to comment that I would expect the space between those tiles to be bridged with some metal at the same height (as in every school I've been in, for instance), but it does look like there's an actual indent. Also, adding a bit more detail to the machinery in the octagonal room might be worth it.
On another note, wish I could help on this. Certainly I've gotten good enough at sketchup to use it as far as I would for mnkin2, and I could easily detail in zBrush, but that's the problem - it would be unrealistic for me to attempt to do much more than detail a nearly finished "base mesh" in zBrush for a project like this. So I'm learning 3Ds Max for what's essentially the most important part, but I know how slow I am to pick up on these sorts of things, even if I were to just use Maya instead.