Brunelleschi's Dome of Florence Cathedral

On August 18, 1418, a competition was announced to design the dome of Florentine cathedral. The main competitors were Lorenzo Ghiberti and Filippo Brunelleschi. Brunelleschi won the competition, but Lorenzo Ghiberti, Brunelleschi’s fellow goldsmith, was the co-superintendent. From the article:

"Imagine the thriving city of Florence in the year 1296. Proud of their city, the Florentines began to build a glorious cathedral, reserving enough space in its design for a huge dome. But there was one problem: no one knew how to erect a dome that would be nearly 150 feet wide and that would begin 180 feet above the ground, atop the existing walls.

Other questions plagued the cathedral overseers. Their building plans eschewed the flying buttresses and pointed arches of the traditional Gothic style then favored by rival northern cities like Milan, Florence’s arch enemy. Yet these were the only architectural solutions known to work in such a vast structure. Could a dome weighing tens of thousands of tons stay up without them? Was there enough timber in Tuscany for the scaffolding and templates that would be needed to shape the dome’s masonry? And could a dome be built at all on the octagonal floor plan dictated by the existing walls—eight pie-shaped wedges—without collapsing inward as the masonry arched toward the apex? No one knew.

When was the dome of the Florence cathedral built?
In 1418 the Opera del Duomo announced a public competition for the construction of the dome with a handsome prize of 200 gold florins—and a shot at eternal fame—for the winner. Leading architects of the time flocked to Florence to present their ideas.

After many uncertainty the Opera del Duomo agreed to make Filippo Brunelleschi the superintendent of the cupola project and appointed Lorenzo Ghiberti, Brunelleschi’s fellow goldsmith, as a co-superintendent. The two men had been rivals since 1401, when they had vied for another illustrious commission, the new bronze doors for the Florentine Baptistery. Ghiberti had won. Now Brunelleschi, whose design for the cupola had been accepted outright, was forced to work side by side with his gallingly successful rival.

The construction of the Dome began on 7 August 1420."