The cathedral is completely explorable, ceiling included. I'm not sure about the front and the ceiling. If somebody likes it i'll wrap it a map later:)
You should probably get a download link up so you can get a better review from others, and by the looks of it, you might want to add textures to everything.
i didn't know about F12. The map is a brainstorming experiment, so i will have to clean a bit before making it a zip. The Cathedral has textures almost completed.