U Seoul Tower is a tower located in South Korea. Though not world famous, it is somewhat well known. But how long will it last with no maintainence?
1 week after people: The power goes out in not just Korea, but all over the world, leaving the tower in the darkness.
20 years after people: Glass begins falling out of the windows, because the caulk has shrunken and cracked.
830 years after people: U Seoul Korea has outlasted mostly all buildings in the world, and has been here for almost a milleneum. But its reign is over, simply from lack of maintainence. The top disinigrates and the tower cascades down.
850 years after people: Korea has now turned into a river.