Basically, you could see for a long way but your eyeballs suck so it largely doesn’t matter. Even with the best telescope and optics on a perfect day you will be limited by the gasses in the atmosphere which scatter light.
Also, Barad-dûr was destroyed when Frodo threw the One Ring into the fires of Mount Doom so it wouldn’t be there.
https://worldbuilding.stackexchange.com/questions/167049/assuming-a-flat-world-and-no-obstacles-how-far-could-you-see
Basically, you could see for a long way but your eyeballs suck so it largely doesn’t matter. Even with the best telescope and optics on a perfect day you will be limited by the gasses in the atmosphere which scatter light.
Also, Barad-dûr was destroyed when Frodo threw the One Ring into the fires of Mount Doom so it wouldn’t be there.
Lol if you’re going to abandon the round earth theory, you might as well dump the concept of an atmosphere, too.
Right, more of an atmo-plane at that point.