The first church-structure was built on the site in the fourth century CE, over the site where Saint Peter, one of Jesus' apostles, was purportedly buried. In the sixteenth century, Pope Julius II commissioned the rebuilding of the church in the Renaissance style, which was designed by several famous architects including Bramante, Raphael, and Michelangelo. The construction was completed in 1626 CE. The basilica has since undergone several renovations and restorations, including the addition of Bernini's famous baldachin over the high altar in the Seventeenth century CE.

circa 306 CE - Modern Period

Early Period (4th-8th Century CE)
The earliest construction of what would become the Papal Basilica of Saint Peter traces back to the reign of Emperor Constantine I (reigned 306–337 CE). Following the Edict of Milan (313 CE), which legalized Christianity in the Roman Empire, Constantine initiated a large-scale building program to accommodate Christian worship. The site chosen for Saint Peter’s Basilica held profound religious significance, as it was traditionally believed to be the burial place of Saint Peter, one of Christ’s apostles and the first bishop of Rome.

Construction of the Constantinian Basilica began around 319–324 CE and was completed by 333 CE. The structure followed the Roman basilica plan, characterized by a longitudinal nave, side aisles, an apse, and a large atrium. Unlike pagan temples, which focused on external grandeur, the interior of Saint Peter’s Basilica was designed to accommodate large congregations. The basilica’s altar was placed directly above what was believed to be Saint Peter’s tomb, reinforcing its religious importance.

Throughout the early medieval period, the basilica suffered from neglect and damage due to the instability of the Western Roman Empire. However, it remained a focal point for Christian pilgrimage, especially under popes who sought to restore its structural integrity and spiritual authority. Pope Leo III (reigned 795–816 CE) and Pope Gregory IV (reigned 827–844 CE) carried out restorations, including repairs to the roof and embellishments to the sacred site.

Carolingian and Medieval Period (9th-14th Century CE)
By the 9th century, the basilica faced increasing threats from Saracen raids, prompting Pope Leo IV (reigned 847–855 CE) to order the construction of defensive walls, known as the Leonine Walls, around the Vatican area. These fortifications were crucial in protecting the basilica and the Christian relics housed within.

During the High Middle Ages, Saint Peter’s Basilica continued to be a major site for religious and political events. The coronation of Charlemagne as Holy Roman Emperor on Christmas Day in 800 CE took place in the basilica, reinforcing the papacy’s role in imperial legitimacy. Subsequent medieval rulers, including Otto I (reigned 962–973 CE), followed this precedent, strengthening ties between the papacy and the Holy Roman Empire.

Architectural modifications continued under various popes, who introduced new chapels, frescoes, and mosaics. However, by the 14th century, the structure was showing signs of serious deterioration. The lengthy Avignon Papacy (1309–1377 CE), during which the papal court was relocated to France, led to further neglect of the basilica. Upon the return of the papacy to Rome, the urgent need for restoration became apparent.

Renaissance Reconstruction (15th-16th Century CE)
By the late 15th century, Saint Peter’s Basilica was in a dire state of disrepair. Pope Nicholas V (reigned 1447–1455 CE) initiated a reconstruction project, commissioning architect Bernardo Rossellino to strengthen the crumbling walls and expand the basilica. However, this effort was largely abandoned after Nicholas V’s death.

A decisive turning point came during the papacy of Julius II (reigned 1503–1513 CE), who envisioned a complete rebuilding of the basilica as a statement of papal grandeur and the Church’s supremacy. In 1506, Julius II commissioned Donato Bramante to design a new basilica, marking the beginning of a century-long architectural transformation. Bramante proposed a centralized Greek-cross plan crowned with a massive dome, an ambitious departure from traditional basilican structures.

After Bramante’s death in 1514, the project passed through several hands, including Raphael and Antonio da Sangallo the Younger, each modifying the original design. However, it was Michelangelo, appointed chief architect in 1547 under Pope Paul III (reigned 1534–1549 CE), who established the definitive form of the basilica. He retained Bramante’s centralized plan but refined the proportions and designed the massive dome that dominates the skyline today.

Completion and Baroque Modifications (17th-18th Century CE)
Following Michelangelo’s death in 1564, his work was continued by Giacomo della Porta and later Carlo Maderno, who was responsible for modifying the basilica into a more traditional Latin-cross plan. Under Pope Paul V (reigned 1605–1621 CE), Maderno extended the nave and designed the iconic façade (completed in 1612), blending Renaissance proportions with Baroque grandeur.

The interior was further adorned with elaborate sculptures, frescoes, and mosaics. One of the most significant additions came under Pope Urban VIII (reigned 1623–1644 CE), who commissioned Gian Lorenzo Bernini to create the baldachin, a massive bronze canopy over the main altar. Bernini also designed Saint Peter’s Square, with its distinctive colonnades symbolizing the Church’s embrace of the faithful.

The basilica remained a focal point for Catholic ritual and diplomacy. The proclamation of the Immaculate Conception dogma in 1854 and the First Vatican Council in 1869–1870 further underscored its theological and institutional importance.

Modern Period (19th Century CE – Present)
By the late 19th and early 20th centuries, Saint Peter’s Basilica faced structural concerns due to aging materials and environmental factors. Conservation efforts intensified under Pope Pius X (reigned 1903–1914) and subsequent pontiffs, aiming to stabilize the foundations and restore artworks damaged by humidity and pollution.

During the 20th century, the basilica became the site of major papal events, including the Second Vatican Council (1962–1965), which reshaped Catholic doctrine and modernized Church practices. In 2000, extensive cleaning and restoration projects were undertaken for the Great Jubilee Year, ensuring the longevity of Michelangelo’s dome and Bernini’s embellishments.

Today, Saint Peter’s Basilica continues to serve as the spiritual and administrative center of the Roman Catholic Church, housing the Papal Altar, the tomb of Saint Peter, and the resting places of numerous popes. Its historical evolution, shaped by theological shifts, artistic advancements, and political transformations, makes it a unique monument in the Christian world.

circa 1590-1676 CE

Apse (Tribune)

circa 1612-1614 CE

Facade
The current facade of the building was designed by Maderno. It is 114.69 meters wide and 45.55 meters tall. It is made from travertine stone and features a large Corinthian column design with a central triangular structure on top, which is topped by 13 statues: Jesus in the center, surrounded by 11 of the apostles, excluding Saint Peter whose statue is located to the left of the steps, and John the Baptist.

The inscription below the cornice on the 1 metre (3.3 ft) tall frieze reads: IN HONOREM PRINCIPIS APOST PAVLVS V BVRGHESIVS ROMANVS PONT MAX AN MDCXII PONT VII (translation;In honour of the Prince of Apostles, Paul V Borghese, a Roman, Supreme Pontiff, in the year 1612, the seventh of his pontificate).

circa 1607-1614 CE

Nave
The current nave of the basilica was designed by Maderno, who expanded Michelangelo’s Greek Cross plan by adding three additional bays to form a Latin Cross, subtly adjusting the dimensions to distinguish his work from Michelangelo’s. He also slightly tilted the axis of the nave—a deliberate adjustment, despite criticism—so that the Basilica’s façade would align with the ancient Egyptian obelisk erected in St. Peter’s Square, which had not been precisely aligned with Michelangelo’s original structure.

The nave, with its towering paired pilasters, maintains harmony with Michelangelo’s design while amplifying the sense of grandeur. The sheer vastness of the interior is so overwhelming that it distorts perception, making it difficult to grasp the true scale of the space. This effect is exemplified by the four cherubs adorning the first piers of the nave, holding holy water basins. From a distance, they appear to be of typical cherubic size, but upon closer approach, it becomes evident that each figure is over two meters tall, and real children cannot reach the basins without climbing the elaborate marble drapery.

The aisles contain two smaller chapels each, along with two larger rectangular chapels—the Chapel of the Sacrament and the Choir Chapel—both richly adorned with marble, stucco, gilding, sculpture, and mosaics. Notably, nearly all of the large altarpieces have been reproduced in mosaic, with the exception of Pietro da Cortona’s Holy Trinity in the Blessed Sacrament Chapel. Two revered paintings from the old basilica, Our Lady of Perpetual Help and Our Lady of the Column, remain in use as altarpieces.

Maderno’s final contribution to St. Peter’s was the creation of the Confessio, a crypt-like space beneath the dome. Designed to provide cardinals and other privileged individuals closer access to the burial site of the apostle Peter, the Confessio is reached via marble steps that are remnants of the old basilica. Encircling its balustrade are 95 bronze lamps, further enhancing the sacred atmosphere of this revered space.

circa 1624-1633 CE

Baldachin of Bernini
The Baldachin, St. Peter's Baldachin (Baldacchino di San Pietro), also known as the Canopy of St. Peter's Basilica, is a magnificent sculptural masterpiece designed by the famous Italian artist Gian Lorenzo Bernini. It was commissioned by Pope Urban VIII in the seventeenth century CE and was installed over the high altar of St. Peter's Basilica (L'Altare di Bernini) in Vatican City, Rome. The Baldachin is made of bronze and is approximately 29 meters tall. It is supported by four massive twisted columns and features intricate detailing and decoration, including sculptures of cherubs, putti, and winged victories.

The Baldachin is a symbol of the power and majesty of the Catholic Church, and is considered one of Bernini's greatest works. It was created as a way to commemorate and honor Saint Peter, the founder of the Roman Catholic Church. The Baldachin's central location in Saint Peter's Basilica, combined with its ornate design and grand scale, makes it an important architectural and cultural feature of the Vatican.

circa 1630 CE

Chapel of the Pieta
The chapel of the Pieta (Cappella della Pietà) is a notable side chapel within Saint Peter's Basilica, renowned for housing Michelangelo’s Pietà, one of the most celebrated sculptures of the Renaissance. Originally sculpted between 1498 and 1499, the Pietà was commissioned for the old St. Peter’s Basilica but was later relocated to the new basilica as part of its grand reconstruction. The chapel itself was designed as part of Carlo Maderno’s early 17th-century expansion, ensuring a fitting space for the masterpiece. Positioned near the entrance on the right, the chapel allows visitors to view the extraordinary detail and emotional depth of Michelangelo’s work, depicting the Virgin Mary cradling the body of Christ. To protect the sculpture, a bulletproof glass enclosure was installed following an act of vandalism in 1972. Today, the Chapel of the Pietà remains a site of deep artistic and spiritual significance, drawing millions of pilgrims and art enthusiasts who come to admire both its architectural setting and the timeless beauty of Michelangelo’s creation.

circa 1866 CE

Monument to Pius VIII
The monument to the pope Pius VIII dates back to 1866 CE. It depicts the pope Pius VIII kneeling with a statue of Christ enthroned behind him. Saints Peter and Paul are shown standing on either sides of the kneeling pope.