They’re not. The Romans built a huge amount and much of their artistic architectural works remaining today were purposely preserved, even if reused for some alternative purpose. Yes, there are some construction techniques they used that contributed to better survival rates than some other structure types. But mostly we’ve ended up with what was lucky enough to survive. Replay the historical tape again and we might be…
You respond to an article detailing the superior durability of Roman concrete with "they just chose to preserve these buildings" and "they just got lucky", cite no sources, and this is the top comment on this thread? Seems HN quality has gone downhill since what I last remember.
Rather than spend my effort fighting a battle others have fought, here is an older HN thread with good commentary on the topic and links to countless previous discussions as well. https://news.ycombinator.com/item?id=22580920