Ya that EXIT sign is really the main focus. The idea of a jail with an EXIT is pretty hillarious. While the place may have had dingy lighting, using long exposures have brought out the color and brightness. Unfortunately you didnt take enough underexposures to cover the highlights in the scene like the door at the far end or the light bulb near us. There is a huge dynamic range between the light sources and the rest of the scene. I dont know how many shots you took for the HDR but you didnt nearly cover the bright end.