What do you call the walls of a dome? Let's say that a building is literally shaped like a semi-sphere. What would you call the wall in such a building? I am asking the question because the wall and the roof are indistinguishable in such a building since there's nothing to separate them. Is there a specific word for walls in such buildings?
Since there are only two surfaces, one inner and one outer, the plural "walls" sounds a little odd, but it might be used anyway. I think most native speakers would understand "the wall" or "the walls" to refer the lower part of the structure, up to some vaguely-defined boundary about two-thirds to three-fourths of the way between the bottom and the apex. From there up, it's the roof (outside) or ceiling (inside).
In other words, I think most native speakers would find all of these sentences perfectly acceptable:
Spiderman climbed up the wall of the dome.
The walls of the dome were painted white.
Spiderman dangled from the dome's ceiling.
Spiderman stood atop the roof of the dome.
Alternatively, in contexts where you don't particularly need to distinguish between the wall(s) and the roof or ceiling, you could say "outer surface" or "inner surface."