First of all, I didn't know that the Upper and Lower Assemby Rooms were actually two different locations until I saw a map of Bath. I'd always thought the Upper Room was the 2nd level of the Assembly Room and the Lower Room was the main floor. Why were they referred as such? It was pretty confusing for me when I read through NA.

Also, this passage from NA chapter 2 added to my confusion, and still confuses me still:

Still they moved on--something better was yet in view; and by a continued exertion of strength and ingenuity they found themselves at last in the passage behind the highest bench. Here there was something less of crowd than below; and hence Miss Morland had a comprehensive view of all the company beneath her, and of all the dangers of her late passage through them.

As I can see they are at a higher elevation in the room, but I can't imagine how. Are they sitting on risers? How is the room arranged so Catherine can see down?