Rooms very often represent different parts of your personality or subconscious, it's a very common motif in dreams because we do nearly everything in rooms of one sort or another in our daily waking lives. So big rooms, like in a factory or warehouse, could represent your bigger thoughts and feelings, or higher spiritual thoughts such as death and angels. It could be that your brain is wanting to connect with 'higher' thoughts while you sleep, the bigger questions we all have about life and death, and perhaps even an afterlife?