the north doors of lorenzo ghiberti were a revelation, a breakthrough in 3-d perspective. he began the work in 1403 and finished 20 years later. the critic vasari called the doors "absolutely perfect, "seemingly breathed into shape, rather than cast and polished with iron tools." it was no surprise, then, that in 1425, ghiberti landed the job of making the east doors, which took another 27 years to finish. michelangelo dubbed them "the gates of paradise," which they are called today. though not yet famous as an architect, filippo brunelleschi won the competition to invent and build a dome to cover the 150-foot octagonal span of the florence cathedral. ♪ ave ♪ maria no one else had any idea how to do this. but brunelleschi's aptitude for precise calculation and his rampant imagination held the day. he would build an egg. he figured a way to use 8 arches, raised like ribs, that held a network of smaller ribs and connecting arches, forming an almost vertical pitch. ♪ ave ♪ maria thus, the risk-taking filippo brunelleschi became the first great architect of the italian