Here's a short film inspired by Arthur C. Clarke's novel Rendezvous With Rama, about exploring a large alien spacecraft from outside the solar system:
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Here's someone else's project, showing a good view of the interior. It's not entirely accurate, because in the novel, the things that looked like Earth buildings weren't, and (with one exception IIRC) had no doors or windows. Still, it gives an excellent idea of the scale. In my imagination, it seemed nowhere near that big.
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I thought about creating a model like that once upon a time, to help me visualize it, but I never got around to it.