Its unbelievable what we do with our history!
Anything that winds up beyond living memory (through attrition) seems to be fair game. A friend once told me, yes, European countries have older stuff around, but we can’t seem to keep anything. Well, Europe has had the same problem, not least because of internecine warfare over a thousand years long. Those lovely oppressive castles (the real ones, not the romantic versions built later) were superceded by technology (torn down, added to, rebuilt) until cannon made them obsolete. They were abandoned, or blown to bits, or pulled apart for the stone.