A setting that takes place a billion (!) years in Earth's future, after several civilizations have peaked and gone, each building upon the remains of the ones before it and then reshaping the planet yet again to it will, to the point that even the layers of accumulated detritus from the past seem unfathomably magical to future inhabitants (e.g. soil that can reshape itself, or windstorms made up of nanomachines that reshape anything they engulf.)
Consider how mines from wars that took place a hundred years ago are still killing people. [1] Imagine some nomads from a hundred years in the future accidentally coming upon these. After a point, technology simply becomes a feature of the terrain, and indistinguishable from nature (another example would be our selective-breeding and cultivations of animals and plants over centuries to develop new hybrids that are now commonplace.)
All of this really piques my interest in what this world will be like in a few thousand years.
"We are like butterflies who flutter for a day and think it is forever"