Brunelleschi's Dome: How a Renaissance Genius Reinvented Architecture

By 1418, Brunelleschi was 41 years old. The son of a successful notary, he had harbored a lifelong talent for solving mechanical puzzles. Brunelleschi grew up “in the shadow” of the construction project that was the Santa Maria del Fiore Cathedral in Florence. He watched the hoists and pulleys used to move the building materials around the site. At 15, he was apprenticed as a goldsmith, a common career track for many successful artists and artisans in this era. Brunelleschi was a talented artisan and reportedly built several innovative clocks, though none have survived to the modern day.

Brunelleschi’s early career was shaped by his rivalry with Lorenzo Ghiberti. The city held a competition to design the grand brass doors to the baptistry in front of the cathedral. The doors were intended as a declaration of religious faith following a severe outbreak of plague. The external threat of a war with Milan also caused concern in the Republic of Florence, as the tyrannical Giangaleazzo Visconti of Milan was threatening to lay siege to the city in his attempt to conquer all of Italy. In Milan, the city’s own grand cathedral was being erected in a Gothic style and “the ‘democracy’ of Florence” (16) feared the autocratic Milanese threat. Brunelleschi and other artists were invited to submit proposals for the 20 bronze panels that would cover the baptistry doors. Their proposals were required to depict Abraham’s sacrifice of Isaac, a biblical story that hinted at the authorities’ desire for “sudden salvation from mortal threat” (17). The competition was held as Milan laid siege to Florence.

Lorenzo Ghiberti was a young Florentine artist of “dubious paternity” (18). In spite of the rumors about his father’s identity, he was amiable and sociable in contrast to the secretive, paranoid, and egotistical Brunelleschi. Ghiberti canvassed many important Florentines for their opinions about his proposal, while Brunelleschi worked in secrecy. Both proposals were deemed brilliant, so Ghiberti and Brunelleschi were invited to work together on the large project. Brunelleschi, noted for his “arrogant self-confidence, irascibility and stubborn refusal to work with others” (20), refused to work with his rival. Offended, he decamped to Rome with a friend, the Florentine sculptor Donatello, while Ghiberti began work on the baptistry doors that would take the next 22 years to finish. Meanwhile, as if in in vindication of the city’s public display of faith, Giangaleazzo died of a fever, and the Milanese troops left Florence.

The people of the Republic of Florence liked to imagine themselves as the inheritors of Rome’s grandiose past, though many of the stories about the city’s link to ancient Rome were inventions. By the 1400s, the city of Rome had dwindled in importance. Only 20,000 people remained among the ruins of the once-great city. Rome had become “a dangerous and unappealing place” (23). After quitting Florence, Brunelleschi travelled to Rome with his close friend, the famous Florentine sculptor Donatello. For as many as 10 years, they lived “like vagabonds” (25), sifting among the vast ruins of the city for inspiration from a bygone era. Brunelleschi studied the ancient ruins, taking notes on architectural traditions such as the deployment of Doric, Ionic, and Corinthian styles that were invented by ancient Greeks and imported to Rome. The precise mathematical formulas and rules for proportion had fallen out of fashion in the Middle Ages. Particularly of note to a young man who had grown up in the shadow of a cathedral without a dome was the Pantheon, the pagan Roman building with a vast dome that had been turned into a church. The compression and tension of the giant structure distributed the weight of the dome onto the walls in such a way that “it seemed to defy the laws of nature” (28). During this time, many of the older Roman texts were being rediscovered, studied, and reappraised after being thought lost. This period of rediscovery would be the foundation of the Renaissance.

Brunelleschi returned to Florence in either 1416 or 1417. He returned to his old neighborhood, beside the cathedral which was now named Santa Maria del Fiore (Saint Mary of the Flower). Like many artists of the era, Brunelleschi was considered “ugly and eccentric” (33). He was unmarried and, by this time, was largely known for his work on linear perspective. This “landmark in the history of painting” (35) allowed artists to portray three-dimensional objects on a two-dimensional surface through techniques such as the vanishing point. Such techniques were seemingly lost following the fall of the Roman Empire, but Brunelleschi rediscovered and refined them, shaping Western art for centuries to follow.

The competition for the design of the dome was announced in August 1418, and focused on the question of “how to build the invisible supports” (38) which would hold up such a vast dome. The quantity of timber needed for such a project would be unprecedented, while the removal of traditional support structures (known as decentering) was “one of the most hazardous operations in the entire building process” (39). To show off his plans, Brunelleschi recruited his friends to build a large model of the dome. With the work of Nanni di Banco and Donatello, his model was “an exquisitely rendered work of art” (41).

Nevertheless, Brunelleschi’s revolutionary ideas—coupled with his refusal to explain how they would work—were met with hostility from the civic leaders. He was dismissed as “an ass and a babbler” (42) and may have been physically ejected. Many stories and rumors spread of what Brunelleschi did during his period of rejection. In one probably apocryphal story, he used an egg to show the feasibility of his design. Whether the Opera del Dumo would award such a prestigious commission based on this “parlor trick” (43) seems unlikely. In contrast, his old rival Ghiberti submitted a simpler project. As with the baptistry doors, the competition came down to Brunelleschi and Ghiberti.

In the 16 years since winning the competition for the baptistry doors, Lorenzo Ghiberti had been very successful. For all his talents as an artist, however, he had little experience as an architect. The fundamental difference between his and Brunelleschi’s plans for the cathedral dome came down to the practice of centering: Ghiberti’s traditional design included it, while Brunelleschi’s innovative approach discarded any need for centering. The officials “dithered and delayed” (45) over the competition. During this period, geopolitical events (such as the end of the Great Schism) caused the Pope to stay in Florence for some time. Brunelleschi designed several small chapels that functioned as proof-of-concept pieces for his “novel scheme of vaulting without centering” (47)--that is, building the dome without the need for temporary wooden supports inside. During this period, a new capomaestro was also placed in charge of the cathedral construction project. Battista d’Antonio was a master mason, more of a builder than an architect. Brunelleschi was appointed as an architectural overseer, but any delight may have been tempered by the simultaneous appointment of Ghiberti to the same post. Another architect appointed to the commission, Giovanni da Prato, harbored a “lusty hatred” for Brunelleschi as he called for the inclusion of windows in the cathedral design (49). Da Prato was ignored. Though Brunelleschi was not yet officially named as the winner of the competition, his design for the dome was chosen.