August 19, 1418
An art competition is announced in Florence to design a dome over the unfinished cathedral of Santa Maria del Fiore. The reason it has been incomplete for 140 years, since 1296, is because current technology (centering and buttressing) can’t yet bridge a span that large without collapsing.
This is an ingenious problem, and the person who wins the competition will be paid 200 florins. Enter Filippo Brunelleschi.