In the Lower Left Image, the ladder/stairwell to what I would call "slightly taller than a  crawl space" 3 feet 10 high, which was used by most tenants as a sleeping space. In Avery's apartment, that is where the secret hatch was created for access into the darkroom. The Top Left Image, is a look down the hallway from the entrance to the apartment. You can see a few steps up to the tall well lit loft area.