> We just don't bother to engineer everything to last forever, because that costs money and has little point to it a lot of the time Unfortunately... 1. Ther

> We just don't bother to engineer everything to last forever, because that costs money and has little point to it a lot of the time Unfortunately... 1. There's no "we". i.e. the entities choosing concrete mixtures and other construction technology do not typically share interests with the people / organizations which inhabit the buildings, except in some very abstract roundabout sense. Which is part of the reason why 2. Concrete construction is usually not engineered to last even a few centuries, let alone "forever". In fact, it is often so poorly engineered (or one might argue: misengineered) that it won't last even a single century, or less than that. Because the principle of costing less money tends to be taken all the way to the point of just barely passing regulatory constraints. 3. ... and those regulatory constraints are often quite lacking. I live in Israel, and a constructor is not even required to guarantee that their building will not-collapse beyond 7 years' time. 4. Actually, a lot of the mass-made soviet-era residential buildings are very well made and almost as good as new (well, considering how they often weren't so great when new). This depends on the specific country, region, period of construction etc.