The concrete dome of the Pantheon in Rome remains stable enough for visitors to walk beneath, and some Roman harbours have underwater concrete elements that have not been repaired for two millennia – even though they are in regions often shaken by earthquakes.
Whence this remarkable resilience of Roman concrete architecture? It’s all down to the chemistry.
Agreed. The article doesn’t really make Roman concrete sound great, it even mentions how limited in availability the volcanic ash they used was.
If we wanted to build to last longer, I imagine not using iron-based reinforcement would get us most of the way there, especially where ice isn’t a concern.