Why don't we learn to build concrete the way the Romans did so that it would last for centuries? Some of our concrete lasts only a few years and probably none of it will be around as long as theirs has.
Those good old Roman structures probably wouldn't be around either if they'd been built in New York City. It is true that they were good structures but they have been blessed with a favorable climate and not subjected to freezing and thawing damage. The Romans made concrete and mortar with lime and pozzolan. The product was much like what we make with portland cement. Many of our structures, like theirs, may also be around a long time, and possibly some of them even longer. Those of ours that are exposed to repeated freezing and thawing and yet survive for a long time will do so because they contain an adequate amount of entrained air and not primarily because of the quality of the cement. Entrained air in concrete is something the Romans didn't know about.