Working with the below in terms of an artificial structure:
…such as a ringworld or an Alderson disk suggests one heck of a setting. Although working out the oddities of atmosphere, sunlight, and how much of that structure is habitable for anything resembling terrestrial life would be a: very complicated and b: far too easy to get wrong. I get the feeling that this sort of thing was a lot easier to pull off in the days of Edgar Rice Burroughs