How much technology for a ring-world to work?

There is this setup that I've seen a few times of a ring-shaped world where people live on the inner side. My question is: what is the minimum advancement of technology for such a thing to happen?

So first:

• can it exist by itself without any crafting of any sort?
• if no, how close? is a ring shaped planet something ever heard of?

And then to live on it, I'm assuming that you'd need to:

• create / maintain an atmosphere (can it work without enclosing?)
• create / maintain gravity (what happens close to the edge?)
• ...other things that will come up...

posted about 10 years ago

Sheraff‭

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