The Great Pyramid holds a record that will almost certainly never be broken: it was the tallest human-made structure in the world for over 3800 years.
(OK technically the Tower of Jericho held the record for ~4000 years, but it was only 28 feet (8.5m) tall; another neolithic archaeological dig could unseat it; that’s not happening with Giza)
In the long run though, I suspect the solid stone construction and ultra stable shape of the Great Pyramid would see it regain the title and keep it for hundreds of thousands of years until it blew away.
Interesting to speculate about, anyway. Let us hope we all live forever.
Maybe the stone cathedrals would last longer?
In any case, the biggest man made structure would probably be an open-cast mine or a slag heap.
Wondering if they made the same mistake as the Spinal Tap guys..