The Story Behind the Architecture and Construction of St. Paul's Cathedral and Sir Christopher Wren

Facade of St. Paul’s Cathedral in London. Photograph Copyright by Mitchell Rocheleau

The Story Behind the Architecture and Construction of St. Paul's Cathedral and Sir Christopher Wren

Within every work of Architecture lies a beautiful story of its creation. The people, events, techniques, materials, failures, and triumphs make up a rich history that is invisible to most eyes. These storylines can be as compelling and beautiful as the final piece of architecture. The story of St. Paul's Cathedral is filled with tragedy, triumph, innovation, and enlightenment. It resulted in the creation of one of Britain's most significant works of architecture. 

Modern London was born from tragedy. In the 17th century, the city was enduring political and religious turmoil. The English Civil War divided the people. London's population was bursting at the seams in an outdated ancient city and infrastructure. The circumstances worsened when a plague swept through the town, followed by the Fire of 1666 that burned the city to the ground. 

After the seemingly endless and relentless devastation, the city was ready for a rebirth. New ideas about art, culture, society, religion, technologies, and science circulated. Traditional ideas were challenged and reassessed.

A small group of men drove the development of these new ideas and their infusion into London society. One of the most notable was Christopher Wren, a young scientist, mathematician, and astronomer. He became interested in architecture and changed the appearance of London through his building projects, most notably St. Paul's Cathedral. 

My first visit to St. Paul's was on a cold, dreary day in February. I knew little to nothing about it. Upon entering the Cathedral, soaked in the rain, I stood in awe at its scale and stunning proportions. I was captivated. The experience prompted me to uncover the story behind the building, its history, Christopher Wren, and the circumstances that led to its creation. 

Wren's Story

Born on October 20th, 1632, Christopher Wren grew up in a household with religious and political values aligned with the Church of England and the monarchy. Both institutions were being questioned and scrutinized at this time in history. He initially showed interest in science, anatomy, and astronomy. While at Oxford in the 1650s, he developed an interest in architecture. He continued to pursue architecture and began to advise the King on architectural matters by 1661. 

Sir John Denham, Surveyor of the King's Works at the time, sent Wren to mainland Europe in 1665 to document and study the new architectural technologies and ideas of the time. Significant developments in building technology were taking place and London did not want to be left behind.

While in Paris, Wren arranged meetings with renowned Italian Renaissance architect Gian Lorenzo Bernini, who was there for a competition related to the Louvre. At that time, Bernini had been the lead architect of the Vatican in Rome for nearly 40 years. Bernini had established himself as one of the Renaissance's most powerful and influential architects, and his reputation preceded him.

Wren observed Bernini closely. He studied his personality, methods of doing business, and architectural ideas. Through this experience, Wren became familiar with dome construction and technology. The encounter with Bernini left a lasting impact on him and provided a model of how a world-renowned architect should operate.

Wren developed the idea that "Architecture was philosophy and politics made in stone." (177 Hollis) He thought that architecture changed over time, reflecting fashion trends that represented the current ideas. This philosophy created a foundation for him to develop his architectural ideas. It helped him detach his architecture from historical traditions and approach his designs freely with more artistic license relevant to contemporary times.  

Wren returned to London in March 1666. Fueled by the inspiration and grandiose architectural ambitions of his Italian contemporaries, he immediately began work on a survey of St. Paul's Cathedral to revitalize the old church. 

The Great Fire of 1666

While Wren was busy iterating on new ideas for the Cathedral, tragedy struck London. On a summer evening, a baker's oven was left on and set fire to the city for nearly five days, burning almost 430 acres north of the River Thames. At the time, the urban fabric of London consisted of tightly packed wooden and straw-thatched houses with eaves overhanging the streets. This type of building was highly susceptible to burning. All it took was a strong summer breeze to spread the fire throughout the city that evening. 

The fire left nearly 100,000 people homeless. Over 13,000 homes were destroyed, along with many cultural icons, one of which was St. Paul's Cathedral. Many people left and set up temporary tents in fields on the city's outskirts. 

Immediately after the fire, plans to rebuild the city and its significant monuments began circulating. The King proclaimed that no rebuilding would be done hastily until a survey and land registrar were completed on the burned area. He also required that brick or stone be the primary building materials allowed in the new buildings. Other provisions, such as road widening and street setback requirements for eaves, were implemented. Minimum standards for road paving, utilities, and other aesthetic architectural requirements were enacted, resulting in a general beautification and functional improvement of the rebuilt area. These ideas became monumentalized in the First Rebuilding Act of 1667. 

The King would entertain several grand schemes to re-organize the city. Wren proposed a master plan for the section of the town destroyed by the fire. He would propose an orthogonal grid pattern of widened streets, an idea he had seen in mainland Europe. He took cues from Bernini's grand gestures in Rome. Wren placed The Royal Exchange, a building representing the city's economic and financial heart, as a critical organizing element in his plan. He felt that the heartbeat of London would rely on economy and finances and thought the urban fabric should reflect this concept.

In his plan, he placed the new St. Paul's at the apex of a triangle, where two primary thoroughfares converged. The scheme was a clear nod to what Wren had seen in Paris and Rome. Unfortunately, the plan was not realized, and the city was rebuilt, reflecting the original street layout and natural topography of the area.  After general regulations were established, the rebuilding process started. 

The city called on the citizens and victims of the fire to help clear the burnt remains of the town. A committee was established to oversee the rebuilding, and Christopher Wren was a key contributor. A separate committee was established to help settle disputes and claims regarding property rights, leasing agreements, and property ownership. Together, these committees' goal was to rebuild in a more orderly, beautiful, healthy, and safe manner that honored the citizens' pre-existing property rights. 

Homeowners had to use their own financial resources to rebuild their homes. However, the reconstruction of many public buildings received funding from the coal tax. London depended on coal at the time, and nearly half a million tons were imported into the city each year from Newcastle, where it was mined. Taxing this import generated a relatively consistent and sustained source of money to fund rebuilding projects. St. Paul’s benefited immensely from this coal tax.  

A massive influx of laborers, masons, and carpenters entered the city to help rebuild, leading to a surge in population growth. Several developers would seize the opportunity to rebuild housing for the city. The most notable developer would be Nicholas Barbon. Barbon built simple, modest-sized homes that complied with the regulations and were quickly repeatable for the skilled laborers. Barbon's business model would prove to be incredibly lucrative.

Parliament passed the second rebuilding act in May 1670. This act combined finances from the King, the city, the parliament, and the church. Bringing together the financial means of all these parties would be complicated. However, it would significantly improve the budget for these projects. 

Although the aggregation of finances from multiple parties would help Wren realize his vision for many building projects, it would also make his job as a Surveyor of Works to Charles II incredibly challenging. He now had multiple clients he needed to keep happy and navigate to realize his projects. 

Dome of St. Paul’s from Millennium Bridge. Image Credit to Jackie

Designing St Paul's Cathedral

St. Paul's remained unused and unsuccessfully restored nearly eight years after the fire. During that time, starting before the fire, Wren proposed six different designs in succession. Some of these versions were attempts to repair and re-roof the old Cathedral. In 1668, masonry from the old building fell, and after studying the structure, Wren proposed that a new building was required, and the old remains could not be used. 

The subsequent design versions showed brand-new buildings, each displaying different qualities and architectural ideas catering to the Cathedral's Design Commission.  In 1672, Wren gained approval from Charles II for what is known as the Great Model. Unfortunately, the Design Commission would not approve this design, and he had to re-design the Cathedral again.

Following the rejection of the Great Model, he proposed an alternative design known as the Warrant Design. In May 1675, both parties approved it, and Wren was directed to proceed with construction. Charles II, the King at the time, told him he could make ornamental modifications to the plan but not change the essential elements of the design. 

Wren saw this as an opportunity and took the liberty to fully re-design the approved drawings. He felt the updates would show a greater harmony with the new modern London developed around the Cathedral. His final constructed version is called the Definitive Design. Surprisingly, unlike previous versions, no physical wooden model was built to show the Definitive Design. The drawings would be "fluid until the moment of actual execution." (Wren Society 1937)

The most noteworthy feature of the Definitive Design was the resurrection of a massive dome from his previous designs, which would reign over London. Wren would design his new dome based on ideas from several historical precedents. These included the Pantheon in Rome, Brunelleschi's Duomo in Florence, and Michelangelo's St. Peter's Dome in Rome. He would learn from the failures and triumphs of each scheme and work to create a dome for London that rivaled the best in history. 

He implemented techniques such as a multi-shell and a compression chain. Brunelleschi implemented the double shell in his design for the Duomo in Florence. Similarly, Michelangelo used it at St. Peters in Rome. The double-shelled dome was a tested approach; however, at the time, Wren's comrade Robert Hooke had been exploring ideas of a more efficient structure to channel the forces of the dome down to the ground and limit the outward forces. Hooke believed the best solution was the conical shape mimicking the force distribution in a catenary curve. Wren implemented the conical dome via a third shell constructed between the inner and outer dome shells. 

This inner shell served as the ceiling for the Cathedral's interior, providing a height proportional to the rest of the structure when viewed from the inside. The interior conical shell would serve as the primary supporting structure for the lantern above. The third shell seen from the exterior was then free to be a beautiful hemispherical shape that rose high above the sky. It was ornamental and not required to bear the weight of the lantern above; therefore, it could be constructed of lightweight timber and metal. 

Areal View of St. Paul’s Cathedral Image Copyright by Spotmatik

Construction of St. Paul's Cathedral

While Wren finalized his designs, the labor team cleared the site and hauled debris. A temporary fence and offices were constructed to keep the citizens out of the construction site. The offices allowed the construction team to be onsite throughout the construction to supervise and work closely with the masons, carpenters, plasterers, painters, and other skilled tradesmen.

The job site and work were closely monitored and documented. Highly detailed accounts of completed work, payments, and progress recordings remain available for us to study. In fact, the site and construction at St. Paul's were so well documented that it has become one of the best collections of information that helped us understand the building process of that time. 

Records show that Wren began regular site visits in 1672. Around that time, a private office was constructed on-site for him, along with a separate office exclusively for his architectural models. Payment to most of the laborers was made at the end of each day. However, other trades, like the stone masons, were paid upon completion based on a certain amount of work they finished. 

The carpenters on the project were responsible for building the scaffolding and formwork required. They needed to ensure this structure was sound enough to hold the weight of the massive stones hoisted into the air. 

The construction team held weekly site visits on Saturday to discuss the project. Wren and his team worked with the tradesmen to derive solutions, discuss modifications, and plan for the following work week. Wren's team presented updated drawings and models to illustrate their concepts. 

The documents and evidence uncovered on-site show that the construction relied heavily on trial and error. Large-scale mock-ups, models, and full-sized drawings were completed and tested. Their failures were analyzed and reworked. The commonly held notion that the drawings were created by the architect and executed on-site by the tradesmen was not true in the case of St. Paul's. We have a record of several failures on-site, such as the collapsing and rebuilding of the crypt arches. The entire team was learning on the job, experimenting with their ideas, and designing as they constructed. 

Historical documents show that many design studies were conducted on the Cathedral's dome around 1693, mainly in the form of models. From the time we have records of Wren laying out the dome on site to arrange the massive piers to the time the dome was finished in 1710, the design and structure of the dome went through many iterations and revisions. 

The final stone of St. Paul's was laid 33 years after it had been started. The city of London changed dramatically over the time the Cathedral was built. Several changes in the Monarchy occurred during that time, of which Wren had to navigate. Wars with other nations affected funding and resources available.

New architectural ideas came into vogue, and tensions developed between Wren and the project committee. Wren's opinions on the final details would be given less consideration. The population continued to grow in the city, sparking development and the creation of an urban fabric that was completely different from when work started. Trade, exploration, wars and colonization changed the economic state of the town. London had emerged as a world capital. The people of London would need time to get acquainted with their new Cathedral as they entered the next century. Although there were mixed feelings about the building when it was completed, it would ultimately become an icon of London. 

City Line View of St. Paul’s Cathedral. Image Copyright © Telling Photography

Criticism of St. Paul's Cathedral

No work of architecture is perfect, and there are always lessons that can help improve the way we design and build in the future. My criticism of St. Paul's is not related to its architecture or aesthetics. Instead, it is a decision made regarding the structural engineering. 

Knowledge of structural foundation design was limited then, and high-quality scientific studies that illustrated soil-bearing capacities were not well documented and known. The soil under St. Paul's Cathedral is comprised of a layer of clay. Under the clay lies a stratum of sand and gravel. It was decided that the foundations were to be set in the layer of clay rather than continuing to excavate down and bear on the layer of sand and gravel. 

Many architects and engineers relied on the Biblical suggestion not to build a house on a foundation of sand. However, in contemporary engineering knowledge, it is now known that sand and gravel can handle a high degree of bearing capacity and, when contained, are well-suited for solid foundations. On the other hand, clay is not an ideal material to build on top of. When exposed to moisture, clay expands and contracts, which can result in differential settlement in a building.

If Wren had decided to deepen the foundations to the sand and gravel layer, St. Paul's structure would have been much more stable. In 1925-1930, extensive work was done to bolster the foundations and repair the damage that had been caused. Fortunately, the problems were solved, and the issues subsided. 

What can we learn

I have returned to St. Paul’s multiple times, and my appreciation and understanding of the forces that made it possible grow with every visit. St. Paul's was created when the British Empire began to thrive and established itself as a global capital. The construction of the Cathedral is closely tied to many significant global events. The Cathedral is a great example of how architecture can be a lens, through which we see and understand our history. Buildings can paint pictures of what life was like when it was constructed. Through the lens and story of St. Paul’s, we can gain insight and perspective not just into London’s history, but into the history of our modern world.

Bibliography

Ackroyd, Peter. London the Biography. Anchor Books, 2000. 

CAMPBELL, JAMES W P. Building St Paul's. THAMES & HUDSON, 2020. 

Downes, Kerry. Sir Christopher Wren, the Design of St. Paul's Cathedral. Trefoil Etc., 1988. 

HOLLIS, LEO. Phoenix: St. Paul's Cathedral and the Men Who Made Modern London. WEIDENFELD & NICOLSON, 2021.