No, the world's infrastructure has never been rebuilt from scratch to higher standards, not in the last few thousand years. We have always built on what already

No, the world's infrastructure has never been rebuilt from scratch to higher standards, not in the last few thousand years. We have always built on what already exists, grandfathered in anything that seemed ok, or was important enough even if not ok, etc. We often live in buildings that far predate any building code, or even the state that emitted that code. We still use bits of infrastructure here and there that are much older than any modern state at all (though, to be fair, if a bridge has been around for the last thousand years, the risk it goes down tomorrow because it doesn't respect certain best practices is not exactly huge).