‘What man, however hard of heart or jealous, would not praise Pippo the architect when he sees here such an enormous construction towering above the skies, vast enough to cover the entire Tuscan population with its shadow, and done without the aid of beams or elaborate wooden supports?’ This was Leon Battista Alberti’s enthusiastic comment when, after a long exile, he went back to Florence. The cityscape had been forever changed by the mighty dome of Santa Maria del Fiore. (Letter attached to ‘Della Pittura’).

‘Pippo the architect’ was, of course, his friend Filippo Brunelleschi, born just steps away from that same Duomo: goldsmith, inventor, sculptor, painter, and finally, architect of the largest masonry dome ever built. Jealous as he was of his creation, Filippo didn’t leave any of his preparatory drawings and projects. Scholars have been speculating for centuries about the secret skills that allowed him to build it. With an outer span of 55 meters (180 feet), built over a high drum, it soars up to 380 feet.

We know that, after having lost the competition with Lorenzo Ghiberti for the bronze doors of the Baptistery, in 1402 Filippo left Florence for Rome, at that time a squalid and dangerous place, in the company of his friend Donatello. The two young artists were nicknamed ‘the treasure hunters’, as they spent most of their time digging the ancient ruins for medals. Filippo must have secretly studied the ancient architectures, with a specific interest for large vaulted buildings; the first was, no need to say, the Pantheon.

The techniques of Ancient Rome, such as the use of concrete, had long been lost. In the Middle Ages Rome was visited mostly by Christian pilgrims, digging the ruins was supposed to be source of bad luck… Filippo and Donatello, with their focus on antiquity, were really the precursors of generations of artists of any kind and nationality that since then would descend to Rome to learn and draw inspiration from the ancient world: in a while ruins were no longer considered bringers of disgrace. The Renaissance had begun.

Brunelleschi must have gone back and forth between Rome and Florence for more than 10 years. Meantime in Florence the high drum of the ‘new’ Cathedral – whose construction had been going on for more than one century – had been finally completed (1410). The wardens of the ‘Opera’ – as to say the authorities who supervised the construction of Santa Maria del Fiore were finally ready to face the building of the dome, that, rivalling in pride with the nearing cities of Siena, Pisa and Orvieto, had to be enormous.

A first competition opened in 1418, with the participation of some 15 architects, some of them came even from across the Alps. No one knew how to deal with the construction of such a gigantic structure, an octagonal dome built on a drum that was already 54 meters (177 feet) above the ground. According to common use, the dome was to be built with the use of a ‘centering’, an inner structure that would support while mortar would dry. Due to the unheard size of the drum, however, the problems were complex.

The amount of timber necessary for the centering, the trees’ length required for the beams, the cost of labor, the machineries to raise the building materials up to the top. Finally, the removal of the centering itself, probably the worst challenge and the most delicate passage. Our Filippo, so far known for his ingenious inventions, his clocks and an almost ‘magic’ trompe l’oeil painting, came up saying he would build the dome without using any centering. Asked to present his project he would deny any further detail.

According to Manetti, his biographer, Filippo was simply thrown out of the assembly and labeled ‘a babbler and an ass’. He confesses that he was afraid to walk the streets for fear of being pointed at as the ‘lunatic’.

A year had passed away and the situation was still critical, the problems still unsolved. Brunelleschi and Ghiberti were at this point in charge of preparing a model for their project. As always, the attitude of the two rivals could not be more different: Filippo worked almost in secret, with the help of strict friends (such as Donatello) who helped him with the decorations, producing a quite large and elaborate model. Ghiberti asked for advice to all his colleagues but in the end presented a much smaller and less detailed work.

Brunelleschi, who officially never won the competition, and never got the prize of 200 florins for it, was in the end selected for the construction of the dome. He was to be sided by Ghiberti, however, who would receive the same wages. On August 7, 1420, 600 years ago, the great adventure began. The construction would take 16 years. At a certain point, with a clever move, Filippo was able to get rid of his archrival

During a difficult passage of the construction, Filippo feigned to have a terrible backache and stayed home. Lorenzo Ghiberti was unable to get away with it and got sacked. Since that moment Filippo was the sole responsible of the Dome. His ingenuity at problem-solving, his inventiveness at constructing very modern and elaborate machines, his way of organizing his team as a complete entrepreneur, taking good care of his workers’ safety as well, his physical ugliness and irascible character made of Brunelleschi a legendary figure. He’s the first architect of the Renaissance, and the first of a well-known series of Italian ‘genii’.

His most innovative invention was an ox-hoist, a machine that was ‘centuries ahead of the technical understanding of the time’, a three-speed, reversible hoist, which a young Leonardo da Vinci reproduced in his sketches. It allowed to spare time and labor when raising heavy blocks of stone up above the cupola.

As we don’t have any original drawing left, and as he concealed most of the structural brickwork of his dome, scholars are still debating about which were the technical solutions that allowed him to build what is still the largest masonry dome ever. Not a hemispheric one, like the smaller and narrower St Peter’s dome in Rome by Michelangelo, but an octagonal one, tremendously heavy and of gigantic size, even bigger that the Pantheon itself. A terrible cupola, whose secret lays in sophisticated technology.

An Italian scholar, Professor Massimo Ricci has spent more than forty years investigating Brunelleschi’s dome and, in the late 1980s has started the construction of a model, 1/5 in size, where he was able to prove that the dome is self-supporting thanks to the use of herringbone masonry. He also points out that the bricks were shaped in a certain way so that they fit perfectly. And that, with the simple use of three ropes that helped masons to wall every brick at the right angle, it was possible to minimize errors.

Ascending the 463 steps inside Brunelleschi’s Dome– recently refurbished – can be hard, especially in a hot summer day, but the emotion and the beauty will, of course, pay you back. The Lantern on top of the main dome, also designed by Brunelleschi, was put in situ in 1471. The inner decoration of the Dome was commissioned to Giorgio Vasari – who was also a Brunelleschi’s biographer. The Last Judgement was completed by Federico Zuccari after Vasari’s death in 1574. Strongly under the influence of Michelangelo, the enormous fresco underwent a delicate and costly restoration in the 1990s.

Brunelleschi’s Dome is regularly opened to the public. To learn more we suggest you to visit the Opera del Duomo Museum.