It's a structure, like a shed or a house, ergo it's technically a set.
No, I'm pretty sure that's not correct. The film glossaries I find online say a set is a constructed environment
, not a structure. If you build an artificial forest or mountainside on a soundstage, that's a set, even if there isn't a building on it. Conversely, if you go out and shoot in a real, existing building, that's not a set, but a location. A set is something you build so you can film or stage action within
it. If it's a structure that's erected for the production and that you only see from the outside, then it's a mockup or a facade. The exterior of the Galileo
was a mockup; the interior, which was built separately (and was larger than the exterior), was a set.