Florence Cathedral: How Brunelleschi Built a Dome Without Timber Centering

Florence Cathedral's dome was more than an architectural silhouette. Built between 1420 and 1436, it solved a problem that had stalled for generations: how to span an enormous octagonal opening without a full timber frame. Brunelleschi's answer was a double-shell masonry dome, tied by ribs and rings, locked with herringbone brickwork, and built with machinery strong enough to lift stone and brick above the city.