10 Dollars Brunelleschi Dome - 5 of 9

Part of a nine-coin series celebrating the domed structures of architectural history, this piece honors Filippo Brunelleschi's solution to a problem that had stumped Florentine builders for over a century: how to vault the crossing of Santa Maria del Fiore without conventional centering — the timber framework normally required to support a dome during construction. Brunelleschi's answer, developed between 1420 and 1436, involved a double-shell brick structure laid in a herringbone pattern, with each course of bricks self-supporting enough to eliminate the need for scaffolding from below.

The dome was built without a single complete set of architectural drawings. Much of the technical knowledge died with Brunelleschi, and the precise mechanics of his construction method remain partly disputed among architectural historians to this day.