I am looking for a word that would contrast with "grounds" when referring to various parts of a site or property. Essentially, the "inside" part of a building or structure.
I don't really like "indoors" because it presupposes doors and feels more like a state of being than a place.
I was initially thinking of the word "proper," but according to my dictionary that doesn't make sense.
I think the comments have indicated I need to be a bit more specific. The word I am looking for is effectively the opposite of the word "grounds". Say, you're taking a tour of Washington D.C. Part of your tour might take you on the White House grounds. Another part of the tour might take you inside, and you would be touring the White House _.
In many cases, you can just say "White House" alone and this will make sense, but I am wondering if there is a word to specifically refer to the place that is NOT the "grounds".