The roof may be a little low, but what's making this worse is that your camera is positioned and angled in a somewhat unaesthetic way. Move it lower and then try to angle it in a way that the image doesn't show a huge chunk of (boring) ceiling, but rather something close a 50/50 between floor and ceiling - in other words: if you imagine a crosshair right in the middle of your image (that would show where the camera is pointing at), at the moment, that crosshair is pointing somewhere at the ceiling, lower that.
Also, what are you using to render (looks somewhat like the editor from Unreal Tournament to me, with a direct screenshot from the tool)? Try to get the program you're using to enable anti-aliasing. That'd help a lot. If it can't, then get a program that allows better rendering (Blender, google for it).
About textures: try to scale them smaller. Especially both stone textures on the objects to the right are scaled way too big. Also, the wooden blocks on the ceiling. And the floor.