Events TooMuchFlorence

The Summer Solstice inside the Duomo of Florence

When the sun touches the Duomo's wall

When the sun passes trough the Brunelleschi’s Cupola

In 1475 the Florentine Mathematics Paolo dal Pozzo Toscanelli built the gnomon, an astronomical indicator to measure the exact position of the sun. The sun penetrates the lantern’s window and passes trough the gnomon; then the sun’s rays pass through small bronze hole of just 4 centimeters in diameter and form a disk of light that hits the marble floor of the Duomo. Where the sun touches the floor inside the Chapel of the Cross, there is a meridian clock and a large marble disk, measuring 90 cm, that indicates noon time.

The marvelous Cupola
The large marble disk
The large marble disk

This astronomical magic happens all year round, but the most impressive phenomenon is during the Summer Solstice marking the highest point reached by the sun into the sky, as well as the longest day.  This event used to be really important for Mathematics and Scholars in the past centuries to understand how and how long the Sun and the Earth move. The gnomon of the Duomo of Florence is the largest ever built in the world with a height of 90 meters.


The astronomical event happens every in 4 or 5 different days in June and  always on June 21st, the Summer Solstice, between 12.30 and 1.30pm. Anyone can attend it and the event is free upon reservation by sending an email to eventi@operaduomo.firenze.it. The entrance is through the door of the Canonici, i.e. the door on the side of the Campanile. If you want to get a better seat I recommend to arrive at least 30 minutes before the event’s start.

When the sun touches the Duomo's floor
When the sun touches the Duomo's floor
When the sun touches the Duomo's floor

TooMuchUpdate 2019

  • Tuesday 11th
  • Friday 14th
  • Tuesday 18th (conference in English language)
  • Thursday 21st

Admission is free upon reservation by email to eventi@operaduomo.firenze.it.


  • Reply
    June 20, 2012 at 6:32 pm

    ciao valentina,

    how early do you think one needs to join the queue for this event tomorrow?

    thanks for your reply!

    • Reply
      June 20, 2012 at 9:09 pm

      Ciao svm! I would say you should be there at least 30 minutes before, since only 150 people are accepted. The entrance is at 12.30pm so you be there not later than 12pm if you want to get in. I would love to see your pictures if you’d like to share them. Enjoy it!

  • Reply
    Visit Florence Museums:Duomo Museum and Attractions in One Ticket | TooMuchTuscany
    March 3, 2014 at 9:02 am

    […] the clock indicates the dusk hour and not midnight, called Hora Italica. Another peculiarity is the Gnomone that you can admire during the Summer […]

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