On April 18, 1506, under the direction of Pope Julius II, the cornerstone of what would become one of the most iconic churches in Christendom—St. Peter’s Basilica in Vatican City—was laid. The event marked not only the beginning of a monumental architectural project but also the spiritual and political ambitions of the Renaissance papacy, which sought to assert Rome’s supremacy as the center of the Catholic world. The construction of the basilica, which would eventually span over a century and enlist the genius of artists such as Michelangelo, Bramante, Raphael, and Bernini, symbolized a pivotal moment in both religious and cultural history.
The original St. Peter’s Basilica had stood on the site since the 4th century, built by Emperor Constantine over what was believed to be the burial place of the Apostle Peter. By the 15th century, the structure had fallen into disrepair. Pope Nicholas V had envisioned restoring it, but it was Julius II who resolved to demolish the aging basilica and construct a new one—grand, imperial, and befitting of the Church’s renewed strength in the age of Renaissance humanism.
The project’s first architect was Donato Bramante, a native of Urbino and a master of classical architecture. Bramante’s initial design envisioned a Greek cross plan surmounted by a massive central dome inspired by the Pantheon and the Hagia Sophia. His vision embraced the Renaissance ideals of symmetry, proportion, and centralized planning, creating a space that would simultaneously evoke the majesty of ancient Rome and the sanctity of Christian worship. The laying of the cornerstone in 1506 signaled the beginning of this ambitious transformation.
However, the basilica’s construction would prove anything but smooth. Bramante died in 1514, and his successors—including Raphael, Antonio da Sangallo the Younger, and ultimately Michelangelo—each revised the design in turn. Michelangelo, appointed chief architect in 1546, famously altered the plan back to a more compact Greek cross and advanced the construction of the dome. His work on the dome, completed after his death by Giacomo della Porta and Domenico Fontana, remains one of the defining elements of the Roman skyline.
St. Peter’s Basilica was not completed until 1626, during the papacy of Urban VIII, who consecrated the church more than a century after the cornerstone was first laid. By then, Gian Lorenzo Bernini had contributed much of the interior decoration and the expansive St. Peter’s Square, framed by sweeping colonnades that invited the faithful into the heart of the Catholic Church. The finished basilica was both an architectural masterpiece and a spiritual beacon, capable of housing 60,000 worshippers and featuring the grand baldachin over the papal altar.
But the story of St. Peter’s is also inseparable from the historical forces it helped to unleash. The funding for its construction came in part from the sale of indulgences, a practice that Martin Luther famously condemned in 1517. The theological dispute that followed helped ignite the Protestant Reformation, permanently altering the religious landscape of Europe and diminishing papal authority outside Catholic territories. In this sense, the laying of the cornerstone was not only an act of faith and artistic ambition—it was also an unwitting catalyst for one of the greatest religious upheavals in Western history.
Today, St. Peter’s Basilica remains a towering symbol of Catholicism, the seat of the papacy, and a site of pilgrimage and wonder. The cornerstone laid in 1506 began a chapter in human achievement that continues to inspire awe across centuries, merging divine aspiration with architectural grandeur in a manner few monuments have ever equaled.
