"The building is over here."
"The building" refers to a building which had been mentioned outside of the given sentence. Therefore I think it's save to assume that we can tell from this isolated sentence that "the building" is already known. So we shouldn't need to say it in Japanese either, right? I don't think that the translation should have その in it.. Oh well, glad we have the report button ^_^
If I have this right, presumably, the context is a building that the listener has already mentioned, probably asking for directions, earlier in the discussion. So その in this case refers to the building being relevant to the other person, while こちら is used by the speaker here to point the listener in the direction they're thinking of.
That building (you were talking about earlier) is this way (pointing or otherwise gesturing at a direction).
This may be a very ambiguous sentence. It's like they're looking at a map and saying, "THAT building is over here." But they should redo this into "Another correct solution:" instead of marking it wrong as nothing in the English sentence indicates the word "that" for "sono".