Brunelleschi's dome

1) "Already at work on the building site, which sprawled through the heart of Florence, were scores of other craftsmen: carters, bricklayers, leadbeaters, even cooks and men whose job it was to sell wine to the workers on their lunch breaks. From the piazza surrounding the cathedral the men could be seen carting bags of sand and lime, or else clambering about on wooden scaffolds and wickerwork platforms that rose above the neighboring rooftops like a great, untidy bird's nest. Nearby, a forge for repairing their tools belched clouds of black smoke into the sky, and from dawn to dusk the air rang with the blows of the blacksmith's hammer and with the rumble of oxcarts and the shouting of orders. Florence in the early 1400s still retained a rural aspect. Wheat fields, orchards, and vineyards could be found inside its walls, while flocks of sheep were driven bleating through the streets to the market near the Baptistery of San Giovanni. But the city also had a population of 50,000, roughly the same as London's, and the new cathedral was intended to reflect its importance as a large and powerful mercantile city. Florence had become one of the most prosperous cities in Europe. Much of its wealth came from the wool industry started by the Umiliati monks soon after their arrival in the city in 1239. Bales of English wool—the finest in the world—were brought from monasteries in the Cotswolds to be washed in the river Arno, combed, spun into yarn, woven on wooden looms, then dyed beautiful colors: vermilion, made from cinnabar gathered on the shores of the Red Sea, or a brilliant yellow procured from the crocuses growing in meadows near the hilltop town of San Gimignano. The result was the most expensive and most sought-after cloth in Europe."

2) "Yet by 1418 what was by far the grandest building project in Florence had still to be completed. A replacement for the ancient and dilapidated church of Santa Reparata, the new cathedral of Santa Maria del Fiore was intended to be one of the largest in Christendom. Entire forests had been requisitioned to provide timber for it, and huge slabs of marble were being transported along the Arno on flotillas of boats. From the outset its construction had as much to do with civic pride as religious faith: the cathedral was to be built, the Commune of Florence had stipulated, with the greatest lavishness and magnificence possible, and once completed it was to be 'a more beautiful and honourable temple than any in any other part of Tuscany.' But it was clear that the builders faced major obstacles, and the closer the cathedral came to completion, the more difficult their task would become."

3) "Filippo, on the other hand, offered a simpler and more daring solution: he proposed to do away with the centering altogether. This was an astounding proposal. Even the smallest arches were built over wooden centering. How then would it be possible to span the enormous diameter called for in the 1367 model without any support, particularly when the bricks at the top of the vault would be inclined at 60-degree angles to the horizontal? So astonishing was the plan that many of Filippo's contemporaries considered him a lunatic. And it has likewise confounded more recent commentators who are reluctant to believe that such a feat could actually have been possible."

4) "Given the experimental nature of Filippo's plan, the 30-braccia limit seems to have been a wise precaution, especially since a sound logic governs the restriction. At a height of 30 braccia the bed joints of the masonry would have risen to form an angle of 30 degrees to the horizontal, or just inside the critical angle of sliding. Friction alone would keep the stones in place up to an angle of 30 degrees, even when the mortar was green; therefore, no centering would have been required until that point. Above that level, however, each course of masonry would incline more sharply, reaching a maximum angle, near the top, of 60 degrees to the horizontal. No doubt it was impossible for the wardens to imagine how these courses might be held in place without centering of some sort."

5) "Religious feasts were numerous in Florence, averaging almost one per week. The populace was accustomed to grand spectacles on these occasions: to the sight of priests and monks in rich habits of gold and silk bearing through the streets the standards of their orders and their most prized relics, all to the tolling of bells, the blaring of trumpets, the chanting of songs and the splashing of holy water. But in 1436 the Feast of the Annunciation, observed on the twenty-fifth of March, was the occasion for a celebration that was spectacular even by the standards of Florence. On this day Pope Eugenius IV processed eastward to the center of the city from his residence in Santa Maria Novella. He was accompanied by seven cardinals, thirty-seven bishops, and nine members of the Florentine government, including Cosimo de' Medici. The procession moved along a 1,000-foot-long wooden platform, six feet in height, that was bedecked with sweet-smelling flowers and herbs. This gangway had been designed by Filippo to carry the pope safely above the crowds teeming in the streets below, a method of crowd control evidently selected in place of a much-used alternative, that of throwing coins into the street in order to scatter the people and keep them from pressing too closely upon the Holy Father. As the entourage turned into the Via de' Cerretani and creaked across the boardwalk in the direction of the thronging Piazza San Giovanni, the new cathedral rose suddenly into view. After 140 years of construction, the time had finally come to consecrate Santa Maria del Fiore."