Re HB claiming pure masonry is better than rebar-reinforced concrete... at least if lifespans>100 years are considered... well maybe, but big domes nowadays are made neither of masonry nor reinforced concrete. The largest reinforced concrete dome was the Seattle "king dome" which had severe problems and was demolished in 2000 after only 24 years. They are still paying off the debt for it, it was never able to pay for itself. The 2nd largest such dome (now the largest after king dome demolished) still apparently in fine shape in Norfolk VA. It's an interesting claim that pure masonry is the most long lived construction method. Incidentally it is not known whether Brunelleschi employed metal reinforcements. Apparently at least some plans said they were to be used but he may have decided during construction they were not needed. If he did use them, they are deeply embedded inside his masonry where nobody can detect them. The techniques B used in building the Duomo apparently are disputed and there is no consensus how he did it.