Ÿ The beginning of the fifteenth century, after a hundred years of construction, the structure was still missing its dome. The basic features of the dome had been designed by Arnolfo di Cambioin 1296. 

Dome Of Florence Cathedral

Ÿ Filippo Brunelleschi, the first great architect of the Renaissance, worked primarily in churches. His most famous masterpiece is the octagonal brick dome he designed for Florence Basilica (an Italian Gothic church), an engineering feat of such difficulty (due to the dome's unprecedented size) that he also had to invent special machines to hoist each section into place.

Ÿ This dome is the most famous transitional work between Medieval and Renaissance architecture

Cathedral of santa maria

Ÿ Although at first glance it appears to be very much a Gothic dome (given its pointed shape and ribbed frame)5, it is considered a transitional work due to Brunelleschi's attention to balanced proportions and simple decoration. It is crowned by a lantern, a rooftop structure with openings for lighting or ventilation.

Ÿ Is an octagonal dome higher and wider than any that had ever been built, with no external buttresses to keep it from spreading and falling under its own weight.

Ÿ The drum or base of the dome was already in place before Brunelleschi received the assignment to complete it.

Ÿ The span of the octagonal drum was 140 feet, a very large span for a dome at that time, especially one without the possibility of external buttressing or supports.

Ÿ Brunelleschi knew that a hemispheric dome (one which is  perfectly rounded) would not be able to span this distance without the use of external buttresses.

Ÿ As a result, he decided to make a pointed dome.  He placed 8 major ribs at the points of the octagon, and 16 minor ribs (two in the space between every two major ribs), all tied together by lateral bands.

Dipesh B. Makwana14SA207

Ÿ The spreading problem was solved by a set of four internal horizontal stone and iron chains, serving as barrel hoops, embedded within the inner dome: one each at the top and bottom, with the remaining two evenly spaced between them. A fifth chain, made of wood, was placed between the first and second of the stone chains. Since the dome was octagonal rather than round, a simple chain, squeezing the dome like a barrel hoop, would have put all its pressure on the eight corners of the dome. The chains needed to be rigid octagons, stiff enough to hold their shape, so as not to deform the dome as they held it together.

Ÿ To lift 37,000 tons of material, including over 4 million bricks, he invented hoisting machines and lewissons for hoisting large stones. These specially designed machines and his structural innovations were Brunelleschi's chief contribution to architecture.

Ÿ The lantern was finally completed by Brunelleschi's friend Michelozzo in 1461. The conical roof was crowned with a gilt copper ball and cross, containing holy relics, by Verrocchio in 1469. This brings the total height of the dome and lantern to 114.5 metres (375 ft).

Ÿ Brunelleschi’s design features a double-walled ovoid shell anchored at the bottom by a 15 meter high tambour eliminating the need for scaffolding and reinforcement. The dome is 44 meters in diameter and 113 meters high topped by a lantern that is accessed by a stairway between the interior and exterior walls of the dome. Florence Cathedral is commonly known simply as The Duomo because of the beauty and magnificence of Brunelleschi's design and its striking impact on the skyline of Florence

Dipesh B. Makwana14SA207