Why are ancient buildings still standing 1500+ years later, but some buildings built like 30 years ago are falling apart?

Question

Why are ancient buildings still standing 1500+ years later, but some buildings built like 30 years ago are falling apart?

In: Other

Answer 1

Many people mention (correctly) survivorship bias, but one thing I’d like to point out as well is this:

I don’t know which building you have in mind, but most visible buildings that old are basically unusable skeletons or partial ruins. There’s a difference between keeping something usable and keeping something “recognisable”. Without adequate and continuous care no building survives that long in its usable format. And lots of modern buildings, if conditions are right (survivorship bias), can survive insanely long in “recognisable” form, but never in usable form, just like ancient ones.