You would think, but often things fail in unexpected ways.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Zinc_pest" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Zinc_pest</a> is destroying thousands of die-cast zinc-alloy toys from the 1930s to 1950s.  Zinc alloys are pretty corrosion-resistant, so this was a surprise.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Cellulose_acetate_film#Decay_and_the_.22vinegar_syndrome.22" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Cellulose_acetate_film#Decay_a...</a> is destroying a lot of historically important documents in libraries that were laminated in acetate during the 1930s to 1950s in order to preserve them.<p>But this kind of thing sometimes happens to architectural materials, too.<p><a href="https:&#x2F;&#x2F;es.wikipedia.org&#x2F;wiki&#x2F;Aluminosis" rel="nofollow">https:&#x2F;&#x2F;es.wikipedia.org&#x2F;wiki&#x2F;Aluminosis</a> is destroying a lot of buildings in Spain in the 1960s and 1970s.  I&#x27;ve seen a similar process underway in buildings built during the same period in Montevideo, Uruguay, but I don&#x27;t know if it&#x27;s from the same cause.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Serpentinite#Serpentinite_reactions" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Serpentinite#Serpentinite_reac...</a> will destroy stone walls pretty quickly if you build them out of olivine-rich rock.<p>Reinforced concrete, especially in chloride-rich environments, will eventually spall from oxidation of the reinforcing minerals.  Some kinds of aggregate, like dolomite, although resistant to weathering themselves, also have a tendency to slowly destroy concrete.<p>You can definitely build a wall that will last thousands of years in the absence of earthquakes, war, gray goo, or acid rain, if you make the wall out of quartz-rich or otherwise slow-weathering, low-TCE rocks like granite, cement it with lime cement instead of Portland cement, don&#x27;t try to reinforce it, and don&#x27;t make it too long, thin, and straight, in order to reduce thermal-cycling stresses.<p>Most of us would never think of most of those issues when we tried to overengineer.<p>The Roman aqueducts have some other interesting virtues, though: due to the arch, they used very little material.  We could probably do better with stainless steel today, but they did pretty darn well with masonry.  I don&#x27;t know if you&#x27;ve ever tried building a masonry arch, but there are some nonobvious considerations, and a mistake can kill you.