Santa Maria Novella, one of the most sublime churches in Tuscany, needs no general introduction. The Wiki article SMV gives a very good overview. The focus of this article is on the amazing meridian dial inside the church itself.

First, I should mention the 2 famous dials on the facade, the subject of much interest, investigation, and analysis including detailed articles by BSS. I plan to feature both separately in due course. On the left is an armillary sphere; on the right is an astronomical quadrant. They are the work of Egnatzio Danti, astronomer to Cosimo I, and were installed c1570.

The Museo Galileo has a comprehensive website here MG and is a superb resource for historical science. Exhibits include 2 of Galileo’s telescopes. In 2007 it held a remarkable dial-based exhibition called The Line of the Sun. The entry for SMN includes all 3 dials and gives a succinct account of their creation and significance. I am adapting / adopting some entries from the museum’s explanations.


Background: Between 1572 and 1575, the cosmographer Egnazio Danti (1536-1586) installed on the façade of Santa Maria Novella no less than three astronomical instruments: a great quadrant with sundials; an equinoctial armillary; and two ‘camera obscura gnomons’. These instruments were designed to be used for new astronomical calculations linked to the project for reforming the Julian calendar…

Meridian Dial: Although Danti designed the dials he was unable to complete the tracing of the meridian line on the floor of the church. He only opened gnomonic holes, first in the glass of the rose window, then on the church’s façade, much higher, and made two openings in the vaulting as well, through which rays of light would pass only during the equinoxes and the winter solstice.

Operation: The entrance of the sunbeam was through the two gnomonic holes. The pinhole on the rose-window would have allowed [the measurement of] time during the entire year. The pinhole on the façade would have allowed the same reading only in the days of the equinoxes and of the winter solstice (IMSS Multimedia Laboratory).


Gnomon holes on the facade in the rose window (70′ high) and just below the pediment


Basilica of Santa Maria Novella . Firenze . Meridian Dial – Keith Salvesen

Basilica of Santa Maria Novella . Firenze . Meridian Dial – Keith Salvesen

Basilica of Santa Maria Novella . Firenze . Meridian Dial – Keith Salvesen

Basilica of Santa Maria Novella . Firenze . Meridian Dial – Keith Salvesen

Basilica of Santa Maria Novella . Firenze . Meridian Dial – Keith Salvesen

Egnazio Danti – Instituto Comprensivo



Wiki cc – header image / close-up

‘photo tsettle’ – gnomon hole positions

All dial photos – Keith Salvesen

SMN (Wiki Arch.)




This article was written a while back, in the pre-Covid era. Now I have a sundial site up and running, this dial and some others from Florence have a new space.

Florence in January.  -8°C at night, zero during the day – but sunny enough in the middle of the day to be able to have coffee or even lunch outside. Apart from the Uffizi, no queues for anywhere. Most significant places on the tourist trail almost to oneself. Despite the cold, there is no frost: the air is so dry that the pavements, piazzas and even the cars are quite clear of frozen white crystals. By the river I caught the electric flash of a male kingfisher flying up from the water to an overhanging bush, his hunting perch. I watched him as he scanned the water below, occasionally diving down and returning to the same branch. Twice, I could see the glint of a tiny fish in his beak. 


Over the years I don’t know how often I have crossed the Ponte Vecchio – or even simply walked to the mid-point to admire the views up and down river from the open areas between the pricey shops. This time I was walking the length of the Vasari corridor that connects the Palazzo Vecchio to the Palazzo Pitti on the other side of the Arno. A section runs straight over the bridge and then passes across the facade of Santa Felicita, into which the Medici family could sneak from the corridor to a large private balcony for spiritual refreshment. Passing the middle of the west side of the bridge, in the ‘tourist photo op’ gap where Cellini’s bust adds to the photogenic view, I have never before looked upwards.


Here, on the roof of a shop, is an ancient sundial, supported by a white marble pillar. An eroded and almost illegible engraving below the pillar records that in 1333, floods caused the bridge to collapse and that “twelve years later, as pleased the Commune, it was rebuilt with this ornamentation”. The sundial itself, with its columnar divisions reminiscent of a rose window, marks the CANONICAL HOURS. The gnomon’s shadow indicates the hour of the day. If the sundial is the ‘ornamentation’ to which the inscription refers, then it is around 650 years old.

If you look closely, you’ll see, halfway up the south face of the hexagonal column, a lizardsundial-ponte-vecchio-florence-1

Seeing the sundial for the first time ever, yet in such a familiar place was a reminder that Florence is a city that demands great attention as one walks through the streets. Many buildings, even unassuming ones, have fine adornments high up that will catch the eye… but only if you are looking out for them.