Look it up (I’d try to find but late, beer and whisky are quite frankly impaired to say the least), it’s fascinating. They used certain mortar ingredients which essentially self heal. Maybe it’s cause am geologist that I find it interesting but something to do with the type of calcium based compounds they used means that any cracks self healed and got actually stronger over time. Then have fun with the rabbit hole of steel reinforced concrete and rust and 70 year lifespan etc etc etc and oh err yeah…. Progress!!