St. Peter’s Basilica: The Crown of Renaissance Architecture

St. Peter’s Basilica in Vatican City is the most important church in Christendom, the largest church in the world, and one of the great monuments of Renaissance architecture. Its construction, which lasted more than a century and involved nearly every major architect of the era, was the most ambitious building project of the Renaissance. St. peter’s is one of the more useful entry points into the ambitions, the rivalries, and the achievements of the period in a single, magnificent structure, and the literature on it is unusually good.

The Old St. Peter’s

The decision to build a new St. Peter’s grew out of the need to replace the old basilica, which had been built by the Roman Emperor Constantine in the 4th century. The old church, a vast timber-roofed basilica, was by the late 15th century in serious disrepair. Its walls were cracked, its mosaics were falling, and the overall structure was unstable. Several popes had considered restoration, but by the time of Pope Julius II, the consensus was that a complete rebuilding was necessary.

The old basilica, despite its condition, was a building of immense historical and religious significance. It was built over the tomb of St. Peter the Apostle, who, according to tradition, was martyred in Rome during the reign of the Emperor Nero. The tomb, located in the Vatican necropolis, was the destination of pilgrims from across Europe, and the basilica was the spiritual heart of Western Christendom.

The destruction of the old basilica was itself a major undertaking. The walls and columns were carefully dismantled, and many of the most precious elements — including the famous porphyry disc from the ancient Roman mint, the porphyry columns from the tomb of the emperor Otto II, and the bronze statue of St. Peter — were preserved. The papal conclaves continued to meet in the partly demolished building, and a temporary wall was built to enclose the tomb of the apostle.

Bramante and the New Design

The foundation stone of the new basilica was laid by Pope Julius II on April 18, 1506. The architect chosen for the project was Donato Bramante (1444–1514), an Umbrian artist who had been working in Milan and who had recently arrived in Rome. Bramante was already famous for his design of the Tempietto (1502), a small circular temple at San Pietro in Montorio, often considered the first perfect building of the High Renaissance.

Bramante’s design for St. Peter’s was a Greek cross plan, with four equal arms extending from a central crossing. The center of the church was to be crowned by a great dome, similar to the dome of the Pantheon but on a much larger scale. The design reflected Bramante’s admiration for ancient Roman architecture and for the centralized, symmetrical plans that he associated with classical perfection.

The Greek cross plan had a number of advantages. It was compact, symmetrical, and well-suited to a centralized liturgy. The four arms would be of equal importance, and the focus would be on the dome at the center. The plan also had disadvantages, however: it was not well-suited to the large crowds of pilgrims who would visit the church, and the orientation of the altar was difficult.

Bramante worked on the project for eight years, but he died in 1514, before the building had progressed very far. The piers that would support the dome were partially built, and the rest of the project was at a very early stage.

Raphael and the Successors

After Bramante’s death, the task of continuing St. Peter’s was given to a series of architects, each of whom modified the design. The first was Raphael (1483–1520), who was appointed co-architect in 1514. Raphael, who was primarily a painter, didn’t have Bramante’s architectural training, but he was a brilliant designer and an excellent administrator.

Raphael proposed a Latin cross plan, with a longer nave extending to the west. This plan would accommodate larger crowds of pilgrims and would provide a more traditional layout for Christian worship. Raphael also contributed to the design of the basilica’s interior, including the design of the famous baldacchino (canopy) over the high altar.

Raphael died in 1520, at the age of 37, and the project was again taken up by other architects. The next was Antonio da Sangallo the Younger (1484–1546), who served as chief architect from 1520 to 1546. Sangallo developed a model of the basilica and a set of detailed drawings, and he made significant progress on the building. He also enlarged the design, increasing the size of the piers and reinforcing the foundations.

Michelangelo’s Dome

When Sangallo died in 1546, the project was given to Michelangelo Buonarroti (1475–1564), then in his seventies. Michelangelo, who had been critical of Sangallo’s design, simplified the plan, returning to a more centralized form. He also redesigned the dome, which he made taller and more pointed than Bramante’s original design.

Michelangelo’s design for the dome drew on his own experience with the dome of Brunelleschi’s Florence Cathedral and on his admiration for the Pantheon. The dome is a double-shell structure, with a brick inner shell and a stone outer shell, connected by ribs. The drum is pierced with large windows, and the dome itself is crowned with a lantern.

Michelangelo worked on the basilica for the rest of his life. He was appointed chief architect in 1547, and he continued to refine the design and to supervise construction. By the time of his death in 1564, the piers of the dome were essentially complete, and the drum was largely built. The dome itself was not completed until 1590, well after Michelangelo’s death, by his pupil Giacomo della Porta, with some modifications to the original design.

The dome of St. Peter’s, completed in 1590, became the model for domes across the Western world, from the U.S. Capitol in Washington, D.C., to St. Paul’s Cathedral in London. It is one of the great achievements of Renaissance architecture, and it’s associated, perhaps more than any other element of the building, with Michelangelo himself.

The Façade and the Nave

While the dome was being built, work proceeded on the rest of the basilica. The most important later addition was the façade and the nave, designed by Carlo Maderno (1556–1629). Maderno, who took over as chief architect in 1603, completed the nave, added the façade, and modified Michelangelo’s design to extend the church into a Latin cross.

Maderno’s nave, completed in 1612, was a major intervention. The nave is wide and tall, with massive piers, rich decoration, and a series of large windows. The nave is often criticized by art historians as a departure from Michelangelo’s centralized design, but it’s a magnificent space in its own right, and it accommodates the enormous crowds of pilgrims who visit the church.

The façade, designed by Maderno and completed in 1612, is a monumental classical front, with ten Corinthian columns and a wide central balcony (used for the pope’s blessings). The façade has been criticized for being too wide for the dome behind it, but it is a powerful statement of the church’s authority and grandeur.

Maderno, Bernini, and the Baroque

The piazza in front of St. Peter’s was designed by Gian Lorenzo Bernini (1598–1680), the great Baroque sculptor and architect. Bernini’s colonnade, with its curved rows of columns surrounding an oval piazza, was begun in 1656 and completed in 1667. The colonnade, with its 284 columns in four rows, was designed to symbolize the embracing arms of the Church.

Bernini also designed the famous baldacchino (canopy) over the high altar, completed in 1633. The baldacchino, a massive bronze structure more than 100 feet tall, marks the spot where St. Peter was martyred. It is supported by four twisted columns, decorated with bronze angels and ornaments, and topped with a globe and cross.

The Cathedra Petri (Chair of St. Peter), also by Bernini, is a dramatic Baroque sculpture enclosing a wooden chair said to have belonged to St. Peter. The sculpture, completed in 1666, surrounds the chair with a giant bronze throne supported by four Doctors of the Church, with a golden sunburst above.

The Interior

The interior of St. Peter’s is one of the great achievements of Western art. The vast space, designed by Maderno and decorated over more than a century, contains works by nearly every major Italian artist of the Renaissance and Baroque.

• Michelangelo’s Pietà (1498–1499), the only work he ever signed, is in the first chapel on the right as one enters. It depicts the dead Christ in the arms of the Virgin Mary, and it is one of the great masterpieces of Renaissance sculpture.
• The tomb of Pope Alexander VII, by Bernini, is a complex sculptural composition combining a portrait of the pope with allegorical figures representing Justice, Prudence, Truth, and Charity.
• The tomb of Pope Innocent VIII, by Antonio del Pollaiuolo, is an early Renaissance bronze tomb with elaborate allegorical figures.
• The tomb of Pope Sixtus IV, by Antonio del Pollaiuolo, is another early Renaissance bronze, with allegorical figures of the virtues.
• The mosaic of the Navicella, a copy of a famous early Christian mosaic by Giotto, decorates the entrance wall.

The interior also contains the statue of St. Peter by Arnolfo di Cambio (c. 1300), a bronze statue whose right foot has been worn smooth by the kisses of pilgrims. The statue, one of the few works of art to survive from the old basilica, is a moving reminder of the long history of the site.

The Dome and the View

The dome of St. Peter’s, which can be visited by climbing 551 steps to the top, offers a spectacular view of Rome. From the lantern, the visitor can see across the city to the hills of Lazio, and on a clear day, the Alban Hills and the Apennines are visible in the distance.

The climb is steep and narrow, and it is not for the faint of heart. But the view, and the experience of standing on the very top of the dome, is unforgettable. It is a reminder of the ambition of the Renaissance builders, and of the human capacity to imagine and execute projects on a scale that seems almost impossible.

The Legacy of St. Peter’s

St. Peter’s Basilica is more than a building. It is a statement of the Catholic Church’s claim to be the universal church, the successor of St. Peter, and the spiritual authority of Western Christendom. It is also a monument to the Renaissance, an embodiment of the era’s ambition, its artistic achievement, and its willingness to undertake projects that would take generations to complete.

The basilica is a masterpiece of collaboration, a project that involved dozens of architects, sculptors, painters, and craftsmen over more than a century. The different contributions are not always harmonious — the façade is wider than the dome, the nave is longer than Michelangelo’s design intended — but the overall effect is overwhelming.

The reading list at the foot of the page is a starting point, not a syllabus. Read what interests you, in any order.

An honest gap. The standard accounts of this period are, in many ways, the accounts of the literate, the urban, and the relatively well-off. The picture you get from the literature is necessarily a partial one, and any responsible overview has to flag the parts it is leaving out.

Sources & further reading

For non-specialists, the most accessible single book on this topic is usually the first in the list. The other two are denser but more thorough.

• Rolf Toman, ed., Rome: The Basilica of St. Peter, the Vatican, the Old St. Peter’s Basilica (2009 in the German edition; English editions of the same)
• Kirstin Bußmann, Pietro in Vaticano: Die Papstgrabungen (for St. Peter’s tomb)
• Any reliable coffee-table book on the basilica, paired with a serious monograph, will do for a first visit

If you want to go further, the bibliographies at the back of any of these books will lead you to the scholarly literature. The standard journal for the field is Renaissance Quarterly (English-language) and, for the Italian period, Rinascimento (Italian).