Brunelleschi’s Dome is one of the great sights of Florence. The world-renowned Cathedral Dome of is an example of ingenious architecture, a joy to behold and one of the symbols of the city.

Here we delve into Florence’s past to discover some intriguing facts about the beloved ‘cupolone‘ and the man who created it.

Cathedral Dome in Florence – 10 Fascinating facts

1. Florence’s dome was a latecomer

The impressive dome was only added in 1420. By then, Florence Cathedral had been under construction for more than a century.

The new Cathedral of Santa Maria del Fiore was intended to be one of the largest in Christendom. The architects – starting with Arnolfo di Cambio, the original designer of the Cathedral – had a grand plan in mind, and the Florentine Comune had plenty of money to spend.

2. The first model for the Cathedral’s dome

A model of a great dome covering the Cathedral was first designed by architect Neri di Fioravante in 1367, but nobody had a clear idea of how to actually build it. In the meantime, rain was pouring in, and this grand cathedral was exposed to the elements.

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3. The competition to build it

To find possible candidates for the job, the Opera del Duomo – the institution founded to supervise the Cathedral work – decided to announce a competition. It was the year 1418. They promised a generous prize for the winner (200 gold Florins).

The keen participants had only six weeks to design their project, showing their model that would finally solve the problem of Florence’s octagonal Dome.

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4. Brunelleschi, an ‘ass and a babbler’

Brunelleschi came up with a mind-blowing idea: the possibility of building a great dome without any centring, the framework traditionally used to hold up the arches and the dome during the building process.

It took a while for the people in charge of the Cathedral to trust him with this solution. To them at first it simply sounded mad, the ramblings of a delusional man. As Ross King writes in his captivating book “Brunelleschi’s Dome“, they openly derided him, calling him ‘an ass and a babbler‘.

5. Florentines call it the ‘Cupolone

Cupolone is the affectionate name used by the Florentines for their duomo. “Cupola’ means Dome and the suffix ‘-one‘ in the Italian language indicates something very big.

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6. Florence Cathedral’s Secret Terraces

To get a better view of Brunelleschi’s Dome you can take a stroll on the Cathedral’s secret terraces. If you join the VIPs Tour of the Duomo Complex, you can enjoy an exclusive close-up view of the Cupola from the terraces that are 32 meters from the ground.

=> This Duomo & Hidden Terraces Tour leads you then to the top of the Dome. You’ll discover all the curiosities about this amazing architectural wonder and get an incredible view over the city.

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7. Florence Dome in numbers

The internal diameter of Florence’s octagonal dome is 45,5 meters, and it weighs a total of 37 tons. This makes it the largest brick and mortar dome in the world.

Its interior is covered with 3600 square meters of frescoes, an impressive “Universal Judgment” painted by Vasari and Zuccari in the second half of the 16th century.

8. Brunelleschi was no architect

Brunelleschi grew up in his family home near Santa Maria del Fiore, under the shadow of the Cathedral. But he wasn’t a trained architect. Instead he started very young as an apprentice to a goldsmith and became master goldsmith at 21. He also studied the science of motion – was fascinated by clocks and invented a few – a passion that likely came in handy when creating some machinery for the construction of the dome.

9. “Maledizione dei fulmini”- The curse of the lighting.

On the 5th April 1492 the lantern on the top of the dome was struck by lightning and was severely damaged. The city of Florence has always remembered that date because the day afterwards Lorenzo de’ Medici, known as the Magnificent, died. Needless to say, this lightning strike was seen as a bad omen.

It happened again in 1601, but this time the gilded sphere that was set above the lantern came down, causing great damage. The sphere – 19 quintals heavy – fell on the piazza. You can still see the spot where it landed, marked by a circular marble stone on the pavement of Piazza del Duomo, on the eastern side of the square.

In Renaissance architecture, lantern means the small structure, usually with decorative arcades, mounted on top of a dome. At times its function is to admit light to the interior, but it is essentially a proportional element in the visual design. (

10. Michelangelo designed the drum for the dome

One anecdote holds Michelangelo Buonarroti responsible for the interruption of the work on the drum gallery on which the base of the dome rests. How did that happen? Michelangelo defined the segment built by Baccio d’Agnolo as a “gabbia per i grilli“, a “cage for crickets” (he meant that it was not visually proportioned), and his comment might have put a stop to the work, probably together with some structural problems that have never been solved, as the drum gallery remains unfinished.

In the Cathedral Museum you can see a wooden model of the dome gallery attributed to Michelangelo. As you walk around the Cathedral, have a look for the only segment of the dome with a gallery (clearly visible in the photo below) – it’s on the side where via del Proconsolo meets via dell’Oriolo.

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Florence cathedral dome
Di Nono vlf – http://Di Nono vlf – Opera propria, CC BY-SA 4.0,

Another curious fact. The dome in miniature.

In the small town of Barberino Val d’Elsa, in the area known as Semifonte, you can find the San Michele Arcangelo Chapel. A curious sight, in the midst of the countryside. It’s a 1:8 copy of Brunelleschi’s Dome, built in 1597 by architect Santi di Tito.

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