Charles's sack of Rome had made a Roman coronation impossible. Bologna, with its large Basilica San Petronio, was chosen as a suitable substitute location, but the change of venue presented significant problems from a symbolic point of view. The geography of the Eternal City and Saint Peter’s Basilica were vital to the centuries-old rituals of the event.
The imperial and papal courts therefore set about faithfully reproducing the symbolic geography of Rome in and around the Basilica of San Petronio. They also worked to ensure that the liturgy of the coronation Mass was performed as it would have been in Rome, drawing up a detailed ordo which specified the texts to be read and chanted in keeping with the age-old traditions.
Although Charles and Clement could not control the location of the ceremony, they were able to control the date: February 24, 1530, Charles’s thirtieth birthday. On the Church calendar, February 24 celebrates the life of Saint Mathias, the man chosen to replace Judas Iscariot as the twelfth apostle. By virtue of the fact that Charles was born on his feast day, Mathias was effectively Charles’s patron saint. The selection of this day drew attention to the relationship, symbolically casting Charles in Mathias’s place. The text of the proper for Mathias’s feast day consistently underscores the close connection between Christ, his apostles, and kingship, making it altogether appropriate for the occasion. The Gospel reading for the day, from the passage in Acts in which the selection of Mathias is described, followed immediately after the coronation itself.
The splendor of the temporary décor set up for the coronation inside the church interior was foreshadowed by the triumphal arches in the new all’antica architectural style of the Italian Renaissance that were set up along the processional route leading from the town hall to the entrance of San Petronio. These were a marked departure from allegorizing mythological or sacred tableaux vivants in the medieval manner set up along the processional routes of earlier coronations.
A wooden ramp led from one end of the piazza to the church entrance; it was lined with parade armaments and with beautiful greenery in gilded basins. At the top of the steps leading to the church’s main entrance portal, a temporary wooden chapel of Sancta Maria Inter Turres was erected; two more such chapels, named for San Gregorio and San Maurizio, were set up inside the church on the left side. These temporary structures helped to “transform” for the occasion the church of San Petronio into the Vatican basilica of St. Peter’s; they stood in for three chapels in St. Peter’s that were important to the coronation ceremony. A disc of porphyry for Charles to kneel on when he was crowned was placed inside the church on the wooden ramp leading from the church entrance to the High Altar. This was a reference to the the rota porphiletica in the pavement of St. Peter’s, which marked the spot whereon Charlemagne knelt when he was crowned by Pope Leo III.
Some idea of how these temporary chapels may have looked comes from a drawing of the temporary tabernacle over the tomb of St. Peter in front of the apse in the Vatican basilica, although the chapels set up in San Petronio were smaller and less monumental. This drawing also shows that in 1530, St. Peter’s was not the magnificently decorated majestic “queen of basilicas” we see today; it was indeed an ungainly, partly dismantled Constantinian/Early Christian basilica of the fourth century, with an unfinished Renaissance centralized church rising within and around it. The Church of San Petronio itself was still under construction; it had yet to be vaulted and the choir was later extended and enlarged. The unfinished condition of both churches may have made the conceit of San Petronio tranformed into St. Peter’s easier to accept at the time. The wooden platform put up for the occasion in the middle of San Petronio was arranged to make the area in front of the high altar appear sunken, to suggest the sunken crypt-like space in front of the high altar in St. Peter’s. According to Vasari, the nave was lined with wooden Ionic colonnades set up for the coronation. If Vasari was correct, these colonnades would have enhanced the intended transformation of San Petronio into Saint Peter’s, which, as the drawing shows, still had its original Constantinian rows of spolia columns lining the nave. An idea of what such an Ionic colonnade would have looked like can be gained from a Fifth-Century Christian basilica in Rome, Santa Maria Maggiore:
The sumptuous decorations of tapestries and luxurious textiles not only gave the occasion and the interior a festive air, but also showcased the quality of textile production in Charles V’s Flemish territories. These brocades, silks, velvets and damasks were made in imitation of and in competition with the prized textiles of the Islamic world and of China.
Such precious stuffs adorned the garb of the spectators as well as the interior of the church. Indeed the most detailed contemporary account of the coronation devotes more space to minute description of what the dignitaries were wearing than to any other subject. Aristocratic portraits of the period give a good idea of what the effect of the costume and textile decorations would have been.