Houses and buildings usually represent your psyche, your inner life. The basement usually represents the subconscious, the attic usually represents your higher mind, or spiritual sense. This seems clear to me based on your dream. The stained glass lookout room sounds very...church like or mystical might be a better word.
Also, the labyrinth in the basement sounds very 'subconscious' to me. A very powerful practice for lucid dreaming in buildings like this is to take out the walls and the ceilings between floors. This integrates your mind. I would look at the labyrinth from above all at once if I were you from the observatory. Bring some light in there and open the windows. Let the light go all the way to the basement.