The Basilica of San Petronio in Bologna does not look special. Its pale pink façade was never completed, so the upper part of the church is still bare with bumpy brown bricks forming its only adornment. The day I visited it was cold, and a thick grey mist hung in the air – a sharp contrast to sunny Florence, which I had just left behind.
Exterior of the Basilica di San Petronio, 1390 A.D.
But I didn’t come to Bologna to see a soggy, half-finished church; I came because I wanted to see a ray of sunlight measure time. One of the things that makes the Basilica of San Petronio unique is that it is home to the longest meridian line in the world. A meridian line is a long line extending due north and small hole in the ceiling that lets a single ray of light hit that line every day at noon. This ray of light indicates, with surprising accuracy, the day of the year as it is marked on the meridian line. When the winter solstice arrives, the ray of light is at such an angle that it reaches the end of the line, whereas during the summer solstice the ray of light hits the beginning of the line. The seventeenth century meridian line in Bologna is so accurate that the citizens of Bologna were among the first to recognize the need for a leap year.
I had hoped that even in the damp, cloudy weather I would see a ray of light striking the floor on the spot marked November 13. In fact, by the time I arrived the sun was beginning to set, and I couldn’t even find the hole in the ceiling. I had to ask someone in my broken Italian, “Where do you use the sun for time?” He grinned at my awkward phrasing but knew what I meant and pointed to a picture of a small golden sun inside one section of the vaulted ceiling. There was a hole in the face of the sun, and, down below, a long meridian line cutting diagonally through the church.
Cassini's Meridian Line in the Basilica di San Petronio, 1655
It’s not surprising that the city of Bologna would have such a clever device built into its cathedral, since the city is home to Europe’s oldest university and has long been a fertile ground for great minds. The man who designed the meridian line in its current form, Giovanni Domenico Cassini, was among those who taught at the university. (An earlier and less successful version of the meridian line was designed by Egnazio Danti.) During my short stay in the city, I visited the museum of the University of Bologna, and I found, among other extraordinary things, a room with tall cabinets full of the printmaking blocks used to illustrate books about varieties of plants and animals. As a printmaker myself, I marveled at the details carved into the wood, even in cases where the identity of the animal portrayed was not clear to me.
A Woodcut in the Museum of the University of Bologna
The next stop on my trip was Padua, home to the second oldest university in Europe. Galileo’s classroom in the University of Padua is still intact, as is the school’s 17th century anatomy theater. Galileo taught in the largest classroom at the school because his classes were so popular that it was the only space that could accommodate them. The anatomy theater, conversely, was claustrophobically tiny, and, given that it would have been lit by candles, it’s hard to imagine how the students in the upper rows would have been able to see anything. I like to think their willingness to stand for hours and watch the action below speaks to their determination to learn from what was a violation of both civic and religious laws: a human dissection. The University of Padua was deeply committed to giving its teachers and students freedom, so it was an ideal place both for someone like Galileo and for students studying anatomy.
Padua is also home to many significant artistic sites, including, most famously, Giotto’s breathtaking Scrovegni Chapel. Less well known is a series of paintings inside the city’s medieval town hall, called the Palazzo Della Ragione. These were originally completed by Giotto and his students, but they were repainted by Nicola Miretto and Stefano da Ferrara after a fire caused damage to the originals. They ring the walls of the enormous building and fill the space with symbolic images – a zodiac, a shepherd smoking a pipe, a women with flowers in her hair. The myriad images perplexed me until I spotted something I had seen before: another meridian line and another sun-shaped hole in the wall. Sure enough, this building was also used to measure time. With this in mind, the symbolic images running around the perimeter ceased to seem so mysterious; they were all symbols for the months of the year. In effect, the entire building was like a large calendar.
Interior of the Palazzo della Ragione, building circa 1218, paintings circa 1450
Bortolomeo Ferracina's Meridian Line Inside the Palazzo Della Ragione, 1761
By this point, I had developed a fascination with the various ways people tracked time in the past, so when I arrived in Venice for a day trip, I was watching for interesting clocks. During my visit to the Doge’s Palace I found several clocks that had twenty-four Roman numerals running around the perimeter in the direction that we would call counter-clockwise. I couldn’t find anything in the informational plaques offering an explanation for these odd devices, so I don’t know why the Venetians used clocks like this. Nevertheless, they provoked me to consider that there is no reason why clocks must run in one direction and not the other or why they have to be marked with only twelve hours.
Clock Inside the Council Chamber of the Doge's Palace in Venice
I had to return to Bologna briefly before the end of my trip, and on my way there I thought about the odd historical moment when these meridian lines were built in Padua and Bologna. The meridian lines were designed at a time when most people believed that the sun revolved around the earth. They saw the angle of the sunlight changing each day and believed that the movement of the sun was real and not apparent.
I can only imagine what it felt like to go to church, see a ray of sun marking the day of the year, and feel that you were at the center of the universe. It’s no wonder that Galileo, who was brave enough to question this assumption, seemed so dangerous back then. And yet, like the meridian lines themselves, he revealed something new about the heavens. The sun does not revolve around the earth, and a year is actually a little longer than 365 days. When we actually look closely at things, we often find something slightly – or radically – different from what we expected. In fact, Cassini, who designed the meridian line in Bologna just twenty-two years after Galileo was imprisoned for his writings, was aware that with such a precise instrument as the one he was building in that church, it would be much easier to collect data and look into Galileo’s theories.
Giuseppe Bertini, Galileo Galilei and the Doge of Venice, 1858, Fresco
This posture of looking closely and remaining open to discovery is what marks cities like Bologna and Padua. It’s not a coincidence that the circulatory system was discovered in Padua or that the first woman to earn a university chair in a field of scientific studies did so in Bologna. Padua and Bologna were exactly the sorts of places where it was possible for these things to happen.
And they still are today. When I was in Padua I met a man who said that he loves Tuscany and Umbria for the beautiful landscapes but his own town for the way people are open to new ideas. With a history like theirs, how could they not be?
A Student from the University of Bologna Continuing Old Traditions with a Laurel Wreath