Location: Florence, Italy
Architect: Filippo Brunelleschi
Year: 1436

Pretty much the dome by which all other domes must be judged, Brunellschi's Duomo caps the Florence Cathedral. Its construction was a radical decision, marking a break with the Gothic style and rejecting the notion that a flying buttress was required to support a massive dome. We will spare you the engineering details and state simply that this dome is an achievement of epic proportions.