I read ”Brunelleschi’s Dome” from the National Geographic February 2014 magazine and learned about his two dome idea for the Florence Cathedral. The cathedral had been without a dome or roof for decades. They knew it needed to be finished, but they did not know how to make a dome that would be 150 feet across and 180 feet in the air that would support all the weight without the renaissance style flying buttresses. They did not know if there would be enough timber, or if they could create an octagonal dome that would not collapse on itself. Filippo Brunelleschi “promised to build not one but two domes, one nested inside the other, without elaborate and expensive scaffolding”. This was a revolutionary idea that took almost 20 years to complete.