“The facade of San Petronio looks like a ploughed field; the rough grooves in the brick have the same colour as the freshly ploughed Emilia plains.” This is how an Italian writer describes the facade of San Petronio, Bologna’s most famous and impressive church. It is the sixth largest church in Europe, preceded only by St. Peter's Basilica at the Vatican, St. Paul’s Cathedral in London, Seville Cathedral, the Duomo in Milan, and the Duomo in Florence. Its size is impressive: 132 metres long by 66 metres wide by 45 metres tall with the facade reaching a height of 51 metres.
The construction of the basilica began in 1390 following a city council decree entrusting the commission to architect Antonio di Vincenzo. The building was dedicated to Petronio, the city’s patron saint with Greek origins who was Bologna’s bishop in the 5th century. Site work began with the expropriation and demolition of numerous medieval buildings adjacent to the Piazza Maggiore. Building construction began with the façade and worked its way back to the apse.
When the architect died twenty-five years later, the plan had evolved into a Latin cross and the church was supposed to reach almost 224 metres long and 150 metres wide. The basilica should have been the largest in the world, but things didn’t go well: the pope didn’t approve of the idea of a church larger than St. Peters. Because of this, in 1650 the papal government began building the Archiginnasio on a site immediately adjacent to the Basilica, literally blocking the realization of its ambitious design.
The construction of the Basilica was put on hold for a long time. This was partly due to lack of funding and the technical challenges of achieving the very high Gothic vaults. However, it was mostly due to the sense of disappointment of no longer having enough space to create the enormous transept with cupola as called for in the original design. However, work did eventually proceed with several famous architects taking part in the process.
Among them were: Jacopo della Quercia, il Vignola, Baldassarre Peruzzi, il Palladio and finally the Roman, Giacomo Rainaldi. Of the original Latin cross plan, only half the shorter arm was completed and both the facade and the interior of the church remain unfinished. It was to be the last large Gothic work in Italy, beginning shortly after the Duomo in Milan but ending much earlier.
The Basilica’s facade was designed using a method of cosmological and esoteric “diagramming”. The result measures 60 metres wide and 51 metres tall and is divided in two horizontal bands. The lower one was clad with marble in the sixteenth century; the upper one remains exposed brick and you can still see the irregular profile which was meant to anchor the final cladding.
The lower section has the three doorways and is clad in stone and red marble. The central doorway, also unfinished, was created by the sculptor Jacopo della Quercia who decorated the door frames with bas-reliefs depicting the story of Genesis. They were so perfect that Michelangelo studied them closely and reproduced some of them in his figures in the Sistine Chapel. The architrave shows scenes from the New Testament, San Petronio, Sant’ Ambrogio, and a Madonna with Child that Michelangelo called, “the most beautiful Madonna of the fifteenth century”.
The two side doors were designed in 1500 and subsequently decorated by several authors. On the sides of the Basilica there are buttresses alternating with full-length windows in stippled marble.
The 65 metre tall campanile was built at the end of the 1400s. Its true uniqueness lies in its four bells. They are from the 15th century and are hand rung by city bell ringing societies using the traditional Bolognese technique that may very well have begun in this campanile. One of the bells is called “the scholar” because it marked the beginning of lessons at Archiginnasio University.
Within the shadows of the highest vault, the Basilica holds some real treasures. The play of light on the plaster and stained glass combine to make the interior, the three naves, and the side chapel even more solemn. Inlaid in the church floor is the largest sundial in the world, created in 1600. The hour is not designated with a line of shadow but rather a ray of light forming the image of the sun.
The twenty-two side chapels contain countless works of art: among them is a “Pietà” from 1500 by Amico Aspertini that contrasts with the Raphaelite style of Michelangelo; a San Rocco del Parmigianino, who Vasari describes in his The Lives as "beautiful in all its parts”; and finally the chapel of San Petronio, a splendid example of 18th century art.
San Petronio also contains two of the most important organs in Italy: the one on the right, from 1475, is one of the oldest organs in existence, while the one on the left dates back to the sixteenth century.
Here is also kept one of the oldest Christian symbols in Bologna: the “Four Crosses”. These crosses may have been erected atop Roman columns by Sant ‘Ambrogio or San Petronio just outside the gates way to spiritually defend the city. The Crosses were later enclosed in little chapels and remained there for over 1300 years until they were located within the Basilica along the side naves where they can still be found today.
Despite its hardships, the size of the Basilica is nonetheless magnificent. It can hold approximately 28,000 parishioners, and over the course of the centuries has hosted numerous stately ceremonies, including the coronation of Charles V in 1530. After the sack of Landsknecht in 1527, the idea of having the coronation in Rome was rejected. Bologna, with its magnificent Basilica of San Petronio, seemed the next best choice.