Florence Cathedral

• 1. Origins And Early Construction

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  The first stone of the Florence Cathedral was laid on the 9th of September 1296 by Cardinal Valeriana. This event marked the beginning of a project that would last 140 years. The city council had approved architect Arnolfo di Cambio's design in 1294. Di Cambio also designed Santa Croce and the Palazzo Vecchio. His plan included three wide naves ending under an octagonal dome. The middle nave covered the area of the old church, Santa Reparata. That ancient structure had been founded in the early 5th century and was crumbling with age. Giovanni Villani wrote about its poor condition in his 14th-century Nuova Cronica. It was no longer large enough for the growing population of Florence. Other Tuscan cities like Pisa and Siena were undertaking ambitious reconstructions during this period. The building of this vast project began with a Gothic style design.

• 2. The Dome Engineering Marvel

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  Brunelleschi won the architectural competition announced on the 19th of August 1418 for erecting Neri's dome. He received the commission despite fierce competition from Lorenzo Ghiberti. Erection of the dome began in 1420 and finished in 1436. The cathedral was consecrated by Pope Eugene IV on the 25th of March 1436. It was the first octagonal dome built without a temporary wooden supporting frame. Brunelleschi employed a double shell made of sandstone and marble. He used brick due to its light weight compared to stone. To lift 37,000 tons of material including over 4 million bricks he invented hoisting machines. A set of four internal horizontal stone and iron chains served as barrel hoops embedded within the inner dome. Each chain was built like an octagonal railroad track with parallel rails. The cross ties and rails were notched together then covered with bricks and mortar. Brunelleschi also included vertical ribs set on the corners of the octagon curving towards the center point. These ribs had slits to take beams that supported platforms allowing work to progress upward without scaffolding. He used a herringbone brick pattern to transfer the weight of freshly laid bricks to the nearest vertical ribs.

• 3. Façade Evolution And Completion

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  The original façade designed by Arnolfo di Cambio was actually begun twenty years after Giotto's death. A mid-15th-century pen-and-ink drawing of this so-called Giotto's façade is visible in the Codex Rustici. This façade was the collective work of several artists among them Andrea Orcagna and Taddeo Gaddi. It was completed only in its lower portion then left unfinished. Grand Duke Francesco I de' Medici ordered its dismantling in 1587, 1588. The competition for a new façade turned into a huge corruption scandal. The wooden model for the façade of Buontalenti is on display in the Museum Opera del Duomo. Work began in 1876 and was completed in 1887. Emilio De Fabris won the competition held in 1864. His neo-gothic façade in white green and red marble forms a harmonious entity with the cathedral and Giotto's bell tower. Three huge bronze doors date from 1899 to 1903. They are adorned with scenes from the life of the Madonna. The mosaics in the lunettes above the doors were designed by Niccolò Barabino.

• 4. Artistic Patronage And Iconography

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  The church is particularly notable for its 44 stained glass windows. These represent the largest undertaking of this kind in Italy during the 14th and 15th century. The windows in the aisles and transept depict saints from the Old and New Testament. Circular windows in the drum of the dome or above the entrance depict Christ and Mary. They were made after designs by Donatello Lorenzo Ghiberti Paolo Uccello and Andrea del Castagno. A large number of artistic works can be overwhelming due to their individual beauty. All major artworks work together to make the cathedral an homage to the Virgin Mary. The iconographic program defined the topic of each artwork and even its placement. It was supervised by the canon Villani during the two centuries it took to complete decoration. Verdon Timothy wrote about Mary in Florentine Art regarding this focus. The intercession capacity of Mary was not always part of the church's theological framework before the 13th century. A new view shifted towards a Christ that had physical existence including human emotions. This incarnational awareness elevated the importance of Mary as the source of the body Christ had incarnated. The central portal featured a monumental sculptural group of the Virgin Mary enthroned with the Christ Child.

• 5. Structural Cracking And Modern Conservation

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  Cracking of the dome was observed even before its construction was completed. The first written evidence about cracks appears in a report by Gherardo Silvani dated the 18th of September 1639. In 1694 Giambattista Nelli and Vincenzo Viviani surveyed the cracks recording two major ones with maximum width. They believed cracks were caused by weight of the dome resulting horizontal thrusts on pillars. Pier Luigi Nervi observed in 1934 that cracks opened and closed with seasons. In winter stone and bricks contracted causing cracks to widen while over summer materials expanded closing them up. In 1955 the Opera del Duomo installed 22 mechanical deformometers read four times a year. These recorded variations in width of major cracks in inner dome. At same time internal and external temperatures were also recorded. This remained in service until 2009. In 1975 a commission appointed by Italian government safeguarded the dome. A survey completed in 1984 counted total of 493 cracks sorted into categories identified by letters A through D. Type A are sub-vertical major cracks starting from ring beam continuing upwards for approximately two-thirds height of dome. They pass through both internal and external layer of even webs. Their range thickness varies between specific measurements depending on web number.