This really looks good. I guess you got the perspective pretty well, especially for a hasty and untrained work. It's just the unpaved wayes and rooms that still look a little to "straight". Maybe a bit of ground structure with shading might help. For example when you're going down without stairs the slope could be presented by ground colour. Or a flat region usually is less illuminated by your "sun" than a region facing it. That was a little clumpsy but I hope you get hwat I mean.
And by the way: what is that channel part on the left that seems to be not connected to anything?