San Petronio Basilica: Bologna’s Civic Gothic Church
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- Medieval
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- Religious
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- Basilica
On this page17 sections
History
San Petronio Basilica is a Roman Catholic minor basilica in Bologna, Italy, dedicated to Saint Petronius, the city’s patron and a fifth-century bishop. The Gothic church was begun in 1390 as a civic foundation rather than as a new cathedral, expressing both devotion to Bologna’s patron and the commune’s ideals of political freedom and municipal autonomy. Bologna’s cathedral is the nearby Metropolitan Cathedral of Saint Peter.
A civic foundation
Bologna’s government decided to build the church in 1388, and the decision entered the city statutes on 1 January 1389. The foundation ceremony, including the laying of the first stone, took place on 7 June 1390. Earlier proposals for a church dedicated to Saint Petronius may date from 1307, but political conditions prevented their realization.
The project required a large urban clearance facing Piazza Maggiore. Medieval blocks were expropriated and demolished, including the Curia of Sancti Ambrosii, much of one city quarter, at least eight churches, and several towers. Financing came partly from a ten-percent tax on pious bequests, imposed especially on ecclesiastical beneficiaries and retained until 1741. During the fifteenth century, income also came from taxes connected with pardons granted for offenses such as gambling and capital crimes. The clergy opposed the undertaking because they had not been consulted and because the church represented an unusually autonomous civic initiative.
The first construction campaigns
Antonio di Vincenzo received the commission for the basilica on 26 February 1390, with advice from Andrea Manfredi da Faenza. Antonio prepared a wooden and plaster model at a scale of 1:12, approximately 15 metres long, but the model and drawings were destroyed in 1402. The intended church was about 183 metres long, with a transept approximately 137 metres wide. It was planned as a Latin-cross building with three naves, side chapels, a domed crossing, an ambulatory around the apse, radial chapels, and probably four campaniles.
The design followed ad quadratum, a geometric system based on squares for proportioning buildings. The central nave was intended to contain ten bays, each about 19 metres square, while the transept would have had seven. The ninth and tenth bays were planned for the choir and ambulatory. Antonio’s concept favoured clear structure, diffused light, and restrained decoration rather than an abundance of Gothic ornament, while seeking an atmosphere associated with ancient Rome.
Progress was slow. When Antonio di Vincenzo died in 1401 or 1402, only two bays, the side aisles, and four chapels had been completed. In 1403, Baldassarre Cossa, the papal legate and an opponent of both the commune and the basilica, sold the stone, timber, and other materials assembled for the work and kept the proceeds. The side chapels had been started in 1393 and were not completed until 1479. The third bay was built between 1441 and 1446, after delays connected with Cossa’s removal and sale of the building materials.
Jacopo della Quercia was commissioned in 1425 to decorate the main portal, but his work ended with his death in 1438. By 1469, the altar stood about 75 metres from the entrance, in the fourth bay. The building had reached the fifth bay, which held a temporary choir, and work on the sixth bay had begun. The chapels were completed later.
Ambitions and interruption
In 1507, the Fabbriceria of San Petronio, the institution responsible for a church’s building works, finances, and maintenance, appointed Arduino degli Arriguzzi as engineer of the works. After studying Brunelleschi’s dome in Florence, Arriguzzi proposed in 1514 an enlarged southern extension with a monumental dome, four transept campaniles, a large apse, an ambulatory, and twelve radial chapels. The projected basilica would have measured approximately 224 metres in length and 158 metres in width, but the plan was never carried out.
The basilica’s civic character also came into conflict with papal authority. In 1508, a large bronze statue of Pope Julius II by Michelangelo was placed on the façade, symbolizing papal rule over Bologna. When supporters of the Bentivoglio family attempted to recover the city, the statue was destroyed in 1511. Its fragments were sold to Alfonso d’Este, Duke of Ferrara, who melted them into a culverin named Giulia.
On 24 February 1530, Pope Clement VII crowned Charles V Holy Roman Emperor in San Petronio. The Holy Roman Emperor was the elected head of a central European political institution whose claims extended across German and Italian territories. Bologna was chosen after the Sack of Rome in 1527 made a Roman coronation there unsuitable, and the ceremony also emphasized papal control over the city.
Pope Pius IV later gave priority to the Archiginnasio, Bologna’s historic university building. Completed in 1562 only about 12 metres from San Petronio, it occupied the site needed for the projected left transept. The original Latin-cross plan could therefore not be completed, and the transepts remained only partly begun.
The vaults and completion of the building works
From 1587, architects debated how to cover the central nave. Francesco Morandi, known as il Terribilia, proposed one solution, while Carlo Carrazzi, known as il Cremona, proposed vaults based on the height of an equilateral triangle whose base matched the width of the façade. Floriano Ambrosini made two wooden models for comparison. No decision was reached before Pope Clement VIII ordered the building site closed on 7 June 1594 and the remaining materials sold.
Girolamo Rainaldi proposed a compromise in 1625 and 1626, with vaults 44.27 metres high. The plan was accepted, and construction resumed in 1646 under Francesco Martini. The apse was built in 1656, the choir windows were installed in 1658, and the vaulting was completed that year. The main-altar staircase followed in 1659, and the ciborium, the canopy over the altar, was completed in 1663. The building works ended in the same year. The fifth bay built under the Terribilia scheme was demolished during the later vaulting campaign, while the sixth bay was completed in 1658. The final masonry vaults replaced temporary wooden roofing but retained a Gothic character even though Gothic design was no longer fashionable.
The façade remained unfinished despite numerous proposals during the sixteenth century by architects including Giacomo Ranuzzi, Jacopo Barozzi da Vignola, Baldassarre Peruzzi, Giulio Romano, Domenico Tibaldi, and Andrea Palladio. Disagreements over the relationship between the lower Gothic zone and a proposed Renaissance upper zone, changing political circumstances, and insufficient financing prevented completion. A competition in 1887 produced no construction, and proposals prepared between 1933 and 1935 were not adopted.
Institutional, musical, and modern history
San Petronio remained a civic foundation until it was transferred from the city to the diocese in 1929. It was consecrated in 1954, and since 2000 it has housed the relics of Saint Petronius, previously kept in the church of Santo Stefano. Its continuing status as a minor basilica and its affiliation with the Archdiocese of Bologna form part of its institutional identity.
A musical organization associated with the basilica was formally established by Pope Eugene IV in 1436. San Petronio became a major centre of sacred instrumental and choral music in seventeenth-century Bologna. Its chapel masters included Maurizio Cazzati, Giovanni Paolo Colonna, and Giacomo Antonio Perti. The church’s bells continue to be used for major feasts, including Easter, the feast of Saint Petronius, the Immaculate Conception, Christmas, and the year-end Te Deum.
The façade restoration carried out between 1972 and 1979 by the Superintendency for Artistic and Historical Heritage became an early example of scientifically based, multidisciplinary conservation of stone materials. The intervention was associated with Cesare Gnudi and the Bologna Centre for the Conservation of Outdoor Sculpture, and its methods later served as a model for conservation projects elsewhere.
In 2002, five men were arrested on suspicion of planning to blow up the basilica and were allegedly connected with Al Qaeda. Italian police thwarted another Islamist terrorist plot against the church in 2006. The stated motive concerned Giovanni da Modena’s fifteenth-century fresco cycle in the Chapel of the Magi, whose Hell scene includes a depiction of Muhammad being tormented by demons.
Remains
Layout, structure, and light
San Petronio is approximately 132 metres long and 60 to 66 metres wide. Built in brick, it has a volume of about 258,000 cubic metres and is the world’s largest Gothic church built in brick. The completed interior contains six square bays in the central nave, each approximately 19 metres on a side, and twenty-two side chapels. The façade faces north and the apse south, an unusual orientation that allows sunlight to enter from the east and west sides throughout the day.
Enormous exposed-brick piers divide the nave. Their elaborately formed bases support sandstone foliate capitals, while the largely unbroken walls emphasize the load-bearing structure. The interior rises without the pronounced linear thrust and strongly expressed rib systems associated with northern European Gothic architecture. Polychrome stained glass adds colour to the broadly diffused light.
The sixth bay contains the presbytery, which extends into half of the fifth bay beneath the broad ciborium erected by Jacopo Barozzi da Vignola in 1547. The interior ends abruptly at a transverse wall, interrupting the intended continuation of the building. The central nave terminates in an apse without the vertical glazing typical of Gothic architecture, while the apse and transepts remain incomplete versions of the projected design.
The unfinished façade
The façade is approximately 60 metres wide and 51 metres high. Its lower zone has marble facing begun between the late fourteenth and early sixteenth centuries. The upper zone remains exposed brick with a faceted profile prepared for a decorative facing that was never completed. The lower section contains Antonio di Vincenzo’s late-Gothic marble base, with polylobed relief panels of saints by Paolo Di Bonaiuto, Giovanni di Riguzzo, and Giovanni Ferabech, also known as Hans von Fernach. A Tuscan-Florentine decorative scheme by Domenico Aimo da Varignana called for white Istrian stone and red Verona marble.
Porta Magna
The central Porta Magna is partly complete and lacks its intended cusp. Jacopo della Quercia carved scenes from Genesis on the jambs, scenes from the New Testament on the decorated architrave, and the lunette, the curved field above the doorway, with the Madonna and Child accompanied by Saints Petronius and Ambrose. Antonio Minello and Antonio da Ostiglia made the prophets on the archivolt, the decorative band following the arch, except for the central Moses by Amico Aspertini.
The reliefs include the Creation, Original Sin, the Fall of Man, Noah’s Ark, and the Binding of Isaac. Michelangelo studied them, and their treatment of the human figure influenced poses in the Sistine Chapel. He reportedly considered the lunette’s Madonna and Child one of the finest Madonnas of the fifteenth century.
The lateral portals
Ercole Seccadenari designed the two lateral portals between 1524 and 1530. Their piers contain biblical scenes, while their architraves show episodes from the New Testament. Alfonso Lombardi’s Resurrection occupies the left lunette. The right lunette contains a Deposition by Amico Aspertini, a Virgin by Tribolo, and Saint John by Seccadenari.
At the two ends of the façade stand late-fourteenth-century trilobed piers built around square cores set diagonally into the corners. Their forms recall Gothic panels or reliquaries and may originally have been intended to end in one or more spires. Along the exterior sides, buttresses alternate with pierced-marble windows that reveal the chapel glazing. The side walls use exposed sagramato brickwork, and near the unfinished left transept is a distinctive book-like two-light window.
Bell tower and bells
The bell tower stands beside the eleventh chapel on the right side and rises 65 metres. Giovanni da Brensa designed it, and it was built between 1481 and 1495. Francesco Morandi designed its wooden trussed bell frame in 1569. Four fifteenth-century bells remain in the tower and are operated entirely by hand using the traditional Bolognese double-beam technique. Gaetano Brighenti filed the bells in 1818 to improve their tuning. The three smaller bells retain their old bronze bearings, while the largest was later fitted with ball bearings and is normally kept upright because of its weight.
The mezzanella, or scolara, traditionally signalled the beginning of lessons at the nearby Archiginnasio. The mezzana was cast in 1584 in an elongated form resembling older bells, possibly reproducing the shape of an earlier lost bell. The Unione Campanari Bolognesi, founded in 1912, has occupied the room below the belfry since 1920. The association preserves local bell-ringing techniques and trains new ringers.
Altars, chapels, and artworks
The counter-façade contains a terracotta funerary monument by Zaccaria Zacchi dated 1526. Some of the robust piers retain fresco panels of saints from the basilica’s first painted decoration, dating from the first half of the fifteenth century. The main altar contains a fifteenth-century wooden crucifix. In the apse, a fresco of the Madonna with Saint Petronius was painted by Marcantonio Franceschini and Luigi Quaini in 1672 from cartoons by Cignani. The basilica also preserves a fifteenth-century wooden choir completed by Agostino de Marchi.
The Chapel of the Magi
Formerly the Bolognini Chapel, the Chapel of the Magi contains a Gothic marble screen designed by Antonio di Vincenzo in 1400 and a wooden altarpiece with twenty-seven carved and painted figures by Jacopo di Paolo. Giovanni da Modena and Francesco Alberti painted cycles devoted to the life of Saint Petronius and the stories of the Magi. The left wall carries a Last Judgment, the Coronation of the Virgin, Paradise, and a Dantean Hell with a gigantic Lucifer and a depiction of Muhammad among the condemned.
Other side chapels
The Chapel of Saint Abbondio, formerly the Chapel of the Dieci di Balia, was restored in neo-Gothic style in 1865. Giovanni da Modena’s frescoes show the Allegory of Redemption and the Triumph of the Church over the Synagogue. Charles V’s coronation took place there in 1530. The Chapel of Saint Petronius was designed by Alfonso Torreggiani for the relic of the saint’s head. The Chapel of Saint Ivo contains statues by Angelo Pio and paintings by Gaetano Gandolfi and Alessandro Tiarini, including the Apparition of the Virgin to Saint Francesca Romana, dated 1615. Two clocks on a pier date from 1758 and were among the earliest Italian clocks equipped with pendulum correction.
The Chapel of Saint Vincent Ferrer contains a 1954 bronze monument to Cardinal Giacomo Lercaro by Giacomo Manzu. The chapel formerly housed the Griffoni Polyptych by Francesco del Cossa and Ercole de’ Roberti, dismantled around 1725 by Cardinal Pompeo Aldrovandi. The Chapel of Saint James contains Lorenzo Costa’s Madonna Enthroned, dated 1492, and stained-glass designs attributed to Costa. A funerary monument there holds the remains of Prince Felix Baciocchi and Elisa Bonaparte and dates from 1845.
The Chapel of Saint Roch contains Parmigianino’s Saint Roch and a Donor, dated 1527. The Chapel of Saint Michael contains Denis Calvaert’s Archangel Michael Expelling the Demon, dated 1582. The Chapel of Saint Rosalia contains Alessandro Tiarini’s Glory of Saint Barbara. Before the fifteenth-century organ case by Lorenzo da Prato, the Chapel of Saint Bernardino contains Amico Aspertini’s four Stories of Saint Petronius, painted in 1531.
The Chapel of the Relics supports the bell tower. The Chapel of Saint Peter Martyr contains a late-fifteenth-century marble screen by Francesco di Simone, while the Chapel of Saint Anthony of Padua contains a statue of Saint Anthony attributed to Jacopo Sansovino. The Chapel of the Blessed Sacrament was rebuilt in the nineteenth century. The Chapel of the Immaculate has Art Nouveau decoration by Achille Casanova, and the Chapel of Saint Jerome contains an altar painting attributed to Lorenzo Costa.
The Chapel of Saint Lawrence contains Amico Aspertini’s Pieta and a bust of Monsignor Bedetti by Federico Monti. The Chapel of the Holy Cross has fifteenth-century devotional frescoes of saints by Francesco Lola, Giovanni Pietro Falloppi, and Pietro di Giovanni Lianori. Its window was made by Blessed Fra Giacomo of Ulm from a design by Michele di Matteo. The Chapel of Saint Ambrose contains a mid-fifteenth-century fresco in the style of Vivarini. The Chapel of Saint Bridget has a polyptych by Tommaso Garelli dated 1477, and the Chapel of Our Lady of Peace contains a Madonna in Istrian stone by Giovanni Ferabech, dated 1394, framed by a painted frontispiece by Giacomo Francia from about 1525.
Organs and musical fabric
Two historic pipe organs stand on choir lofts on either side of the main altar. Lorenzo di Giacomo da Prato built the organ on the right side of the presbytery between 1471 and 1475. Despite later alterations, it is described as the oldest surviving Italian organ and the first with independent registers, allowing separate groups of pipes to be selected and controlled independently. The organ opposite it was built by Baldassarre Malamini in 1596.
Francesco Traeri altered the organs in 1691, Vincenzo Mazzetti in 1812, and Alessio Verati in 1852. Both were restored by the Tamburini firm in 1986. The Lorenzo da Prato organ retains its original mechanical action, a 54-note manual, and a 20-note lectern pedalboard. The Malamini organ retains its original mechanical action, a 60-note manual, and an 18-note lectern pedalboard. Both instruments preserve split or short-octave features in their keyboards and pedalboards.
Crosses, archive, and meridian instrument
Four historic crosses are arranged inside the basilica along the side walls in the positions associated with their former urban arrangement. Tradition held that Saint Ambrose or Saint Petronius erected them between the fourth and fifth centuries on Roman columns outside the gates of Bologna’s first selenite-wall circuit. They were transferred into the basilica in 1798 with relics found at the column bases. The visible crosses are later renewals dating from the tenth to the twelfth centuries.
The Cross of the Apostles and Evangelists stands to the left on entering and was renewed in 1159. It formerly stood near Porta Ravegnana. Opposite it is the Cross of the Holy Martyrs, once located halfway along present-day Via Monte Grappa. Near the main altar are the Cross of the Holy Virgins, formerly at the intersection of present-day Via Farini and Via Castiglione, and the Cross of All Saints, formerly at the junction of present-day Via Carbonesi and Via Barberia. A marble plaque above the Cross of the Holy Martyrs records the former locations and their transfer to the basilica.
The historical archive inside San Petronio contains 724 volumes, bundles, and packets concerning the administration of the building works. It includes statutes, regulations, acts, and resolutions, together with income records, general accounts extending almost continuously from 1421 to 1810, cash books from 1439 to 1938, ledgers from 1429 to 1935, and creditor and debtor books from 1415 to 1921.
Egnazio Danti constructed the first meridian instrument in 1575 and 1576. Continued alterations to the building, particularly the demolition of the end wall of the left nave in 1656, later made the original gnomon unusable. Giovanni Domenico Cassini was commissioned on 12 June 1655 to construct a replacement meridian line, completed in December 1657. A meridian line records the Sun’s position at local noon. At San Petronio, sunlight passes through a 27.07-millimetre aperture 27.07 metres above the floor and projects an inverted image of the Sun onto a marble line 66.8 metres long.
Cassini called the instrument a heliometer because it could measure the Sun’s apparent diameter. He also used it to calculate the obliquity of the ecliptic, the tropical year, the dates of equinoxes and solstices, atmospheric refraction, and changes in the Sun’s apparent diameter. The instrument probably provided the first experimental verification of Kepler’s second law of planetary motion. Eustachio Zanotti completely reconstructed the marble line in 1776, replacing its central iron rod with brass and copper bars and adding zodiac signs and scales for gnomonic height and Italian clock hours.
The original measurements were checked by Federigo Guarducci in the early twentieth century and again by Giovanni Paltrinieri in 2005. The later check found that the present vertical point had shifted 1.8 centimetres north and 0.7 centimetres east from its former position. The line had also subsided by almost 42 millimetres at the winter-solstice plate compared with its beginning. A complete-size cast of the Porta Magna made by Oronzo Lelli in 1886 is preserved in a cast court of the Victoria and Albert Museum in London.
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