Brunelleschi's Dome - Florence, Italy

At the heart of Florence stands the Duomo, the Cathedral of Santa Maria del Fiore. Begun in 1294, and designed by the architect, Arnolfo di Cambio (c.1240-1300/1310), the building is a vast basilica formed around a domed tribune, with two other attendant buildings – the Campanile and the Baptistery – each clad in white, green, and red marble. To the south of the cathedral, in the adjacent Piazza del Duomo, there are two niches in the neighbouring building, each containing a white marble statue of a seated man. The first is of Arnolfo, who sits looking rather formal and composed. Next to him, the second statue sits in a very different, much more dynamic, pose. The figure’s eyes are raised and seem to be staring, intently focussed upon the dome of the cathedral towering far above. Resting in the figure’s lap is a large sheet of paper over which the figure's hand is poised holding a set of dividers. This statue depicts Filippo Brunelleschi (1377-1446), the capomaestro (architect-in-chief) who designed and built the magnificent dome which crowns Arnolfo’s basilica.

The dome of Santa Maria del Fiore – or “Brunelleschi’s Dome” as it is perhaps better known – is an unequalled feat of engineering. When the main body of the basilica was completed in 1418 no one had yet managed to work out how such a monumental dome of brick and stone could be raised over such a vast space. The cathedral itself had been built on pure faith that somehow someone – with God’s help – would find a solution to this architectural challenge. That person was Filippo Brunelleschi. Filippo was a pioneering architect and engineer. In his early years he had spent time in Rome, examining the ruins of the ancient city, studying what was left of the old Roman capital. This period of study evidently paid dividends because he would later build upon and surpass the techniques of the Romans, confounding the architectural wisdom of his own day and in so doing transforming the art and science of architecture.

But Brunelleschi had to fight hard to realise his ambitions, competing with antagonistic rivals to secure each stage of the project to build the dome and the marble lantern which would surmount it. As a boy growing up in the shadow of the slowly growing basilica, he had been fascinated by the machinery used to build the cathedral, and in many ways perhaps his greatest triumphs – the machines and ingenious devices which he designed in order to construct such a vast and seemingly impossible project – have since been lost to us. Some of these large machines survive as drawings only – several of which were later drawn by the hand of Leonardo da Vinci (1452-1519), who, like Filippo before him, as a youth had been similarly fascinated by the methods employed in the basilica’s construction; and who – it is thought – whilst only a young man, and still only an apprentice, eventually assisted in the raising of the brass orb and cross which sit atop the marble lantern that finally completed the centuries long project of building the cathedral in 1461. A few of the smaller machines and tools have been preserved and can be seen when visiting the dome itself. Also, little noticed by the vast numbers of tourists who visit the cathedral everyday, two pulleys remain left in place, forgotten by the original work men – one of which can be seen if you follow the gaze of Brunelleschi’s statue to one of the tribune morte (blank tribunes), the niches which flank the main drum beneath the cupola.

The great engineering achievement of the dome itself consists in both the design and the method of its construction. Brunelleschi revolutionised the building of such domes in two ways. Firstly, he created the dome in two parts, in effect creating two domes one inside the other, thereby reducing the weight which the structure exerted on top of the walls of the basilica below, and, secondly, he employed an innovative pattern of brickwork, thereby also alleviating the stresses within the fabric of the dome itself and making the dome effectively a self-supporting structure. This alone was perhaps Brunelleschi’s most conspicuously visible display of his pre-eminent genius.

When he first submitted his proposals for building the dome he confounded the cathedral’s overseers, the Opera del Duomo, by telling them that he could construct the cupola without the aid of a supporting scaffold within; a suggestion which must have at first sounded like madness until properly explained. The dome would be self-supporting due to a combination of wooden and stone rings concealed within the structure and augmented by a herringbone pattern of brickwork, which is still clearly visible to anyone ascending the dome today. It’s also a great testament to Brunelleschi’s intense eye for such precision and detail that he also took pains to ensure the safety of the men employed in building the dome, such that there were only three fatalities during the building works, and only one of which was due to a fall during the actual dome’s construction.

Yet the dome was remarkable in ways which reached beyond simply its ingenious method of construction, for it was also seen as an instrument with the potential for improving scientific knowledge. Not simply an expression of faith made manifest in bricks and mortar, it was also seen as an instrument for examining the mechanics of God’s Universe. And as such this was recognised by one of the greatest mathematicians and astronomers of the Renaissance, Paolo Toscanelli (1397-1482). Toscanelli and Brunelleschi became friends around 1425 – and both men were very alike, wholly committed to their work, uncaring of their appearances, not wasting time with luxuries, they were instead each dedicated to their life-long projects of refining their own areas of expertise. It is said that Toscanelli helped Brunelleschi by instructing him in Euclidean geometry, and, perhaps unwittingly, Brunelleschi posthumously repaid the favour in the form of his greatest construction – the dome itself – which allowed Toscanelli to turn the entire ediface into an enormous sundial. By installing a bronze plate, la bronzina, with a small aperture (of a circumference not exceeding one thousandth of its height above the ground) at the base of the lantern. This small hole then channelled a beam of light which fell some 90 metres below to a special gauge laid out on the floor. The device allowed Toscanelli to calculate what he perceived to be the motions of the Sun (in his contemporary geocentric view of how the solar system operated), enabling him to calculate with much greater accuracy than anyone before him the precise moments of the summer solstice and the vernal equinox. These calculations were of great assistance to the Church authorities, who could use them to better determine the dates for such moveable feasts as Easter. They were also of great benefit to navigation at sea as well, and it is known that Toscanelli corresponded to this end with no lesser navigator than Christopher Columbus (1451-1506). The sundial was later refined by the mathematician, engineer, astronomer and geographer, Leonardo Ximenes (1716-1786) in 1754, who used the device to calculate variations in the angle of the inclination of the Earth’s axis with respect to the plane of its elliptical orbit around the Sun (our modern heliocentric view). This ‘function’ of the dome was restored to full working order in 1996. A brass meridian line has been set into the floor of the Capella della Santa Croce (on the north side of the cathedral) which is not usually accessible to the public, but the line can still be glimpsed from the balcony, high up inside the dome when descending from the lantern.

I first visited Florence in early 2004 and had been captivated by the Duomo. That first visit was only a very brief overnight trip, contributing to an exhibition being held at the Palazzo Pitti. That evening I had crossed the Ponte Vecchio and wandered up to the Duomo which stood with its polychrome marble and its warm red terracotta tiles all brightly lit up against the stark black night sky. The effect on me was profound. I knew I would one day have to come back and explore the city properly and the Duomo in particular. Eight years later and I have just returned from five days doing exactly that. For a historian interested in the Renaissance in general, Florence is a city of incomparable fascination. There is so much to see and examine that a single trip is unlikely to suffice, and so I still hope to go back again one day. On this particular trip though, I made the Duomo and Brunelleschi my focal point. I took with me an indispensable guide. Brunelleschi’s Dome, How a Renaissance Genius Reinvented Architecture, by Ross King (Penguin, 2000), is an excellent and highly readable account of Brunelleschi’s life and his greatest work, the Dome of Santa Maria del Fiore. It really is worth reading up and studying the dome before visiting so as not to miss the many fascinating small details which make it such a marvel to contemplate. 

However, it can be hard to fully appreciate the construction amidst the constant press of other tourists surging up through the narrow confined spaces between the two shells of the dome itself, pushing one ever upwards between the curving walls, which are in a deplorable state, covered in thoughtless graffiti. Then, scrabbling for a foothold on the narrow ledge surrounding the marble lantern, where it’s equally difficult to stand looking back against the hordes of cameras all clawing for space, and all intent on pointing their lenses out towards the understandably breathtaking panorama of the city far below. When I visited it seemed as though no one was really interested in the actual fabric of the building on which they were standing, through which they had laboriously climbed and threaded their way, following in the footsteps of Filippo and his Masons, and Michelangelo too, who had climbed the dome to study it as part of his preparations for the building of the dome of St. Peter’s in Rome. How many of these visitors I wondered knew of the genuine technical achievement which lay beneath their feet? – Such a remarkable construction which had changed and advanced architecture by a single and immeasurable giant stride; an achievement made all the more remarkable for simultaneously having been constructed during a period of tumultuous uncertainty, a time of pestilence and warfare. 

In many ways Brunelleschi’s Dome represents the great achievements which now characterise the Renaissance – it represents a tangible embodiment of the meeting of both profound vision and vaunting ambition with the refinement of art and beginnings of genuine science. Brunelleschi’s Dome perhaps represents for us (in our present-day historical perspective) the profound faith in human aspiration and human achievement which re-emerged in the Renaissance era, as much as it also undoubtedly represents an expression of its makers’ unshakeable faith in the divine glory to which they dedicated their incomparable labours – an achievement which remains physically unsurpassed even into our own era.

All the photographs accompanying this article were taken by me on my recent trip to Florence.

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