The Saint Peters Basilica, located in Vatican City, Rome, is one of the most magnificent examples of renaissance architecture in the world. Built over the burial site of St. Peter, the first bishop of Rome, the Basilica is located in St. Peters Square and is visited by millions of Christian pilgrims every year. The new Basilica replaced the old one when its construction began in 1506. True to the Christian faith in the resurrection, the glory of the Basilica was restored over time from its past of damaged structures and mutilated artwork. The story of the reconstruction and restoration of St Peter’s Basilica also provides unique examples of innovative techniques for architectural conservation that was at the helm of the marvellous story.

The timeline of the restoration and reconstruction of the famous and prized structure is summarised in the following paragraphs. 

Timeline of restoration: Saint Peter's Basilica - Sheet1
St. Peter’s Basilica_©Sergey

Old St Peter’s Basilica | Saint Peter’s Basilica

Following the crucifixion and burial of St Peter in 64 CE, the construction of the old Basilica was commissioned on the site of his tomb between 326-333 under the reign of Emperor Constantine and was completed in approximately 30 years. In addition to regular mass service, the Basilica was also used for religious and cultural ceremonies, including Papal coronations. It featured a five-aisled plan, a central nave, and two smaller aisles on the side with a capacity of approximately 3000 – 4000 people. 

Although the church was constructed in brick and wood, it was adorned with marble columns, colourful mosaics, and detailed frescoes. Some of the most remarkable frescoes include the Navicella or Bark of St. Peter, which shows the apostle walking on water; Epiphany, which depicts a Christian feast day; and; a standing Madonna. These mosaics are preserved in different museums and churches around the country today.

Timeline of restoration: Saint Peter's Basilica - Sheet2
plan of old St. Peter’s Cathedral_©

New St Peter’s Basilica

After a life of almost 1200 years, with an evident compromise in the structural integrity of the Basilica, Pope Julius II decided to demolish the building and build a new basilica in its place. The Pope called for a complete redesign and demolition of the Basilica through a competition. The winner of the competition was Donato Bramante, who proposed the new church in the form of a Greek cross, with a dome inspired by the Pantheon and Brunelleschi’s dome at Santa Maria del Fiore in Florence. Many of the other designs received for the new Basilica are still housed at the Uffizi Gallery in Florence.

In 1506, the construction of the new St Peters Basilica finally began, and it was completed over a century by the end of 1626. 

Some of the other milestones concerning its construction are as follows.

1503: Bramante hired to build a new Basilica
1546 – 1547: Michelangelo was selected as the architect of St. Peter’s Basilica and produced his first wooden model of Brunelleschi’s dome.
1547 – 1590: The construction of the dome
1626: Consecration of the new Basilica of St Peter
1656 – 1667: St Peter’s Square was built 

Timeline of restoration: Saint Peter's Basilica - Sheet3
interior of old St. Peter’s Cathedral_©clay banks

1999– upon the commissioning of Pope John Paul II, the restoration of the Saint Peter’s Basilica façade started in 1999. The façade, earlier believed to be monochrome, was revealed to be colourful after scrubbing off pollution, dust, and dirt. This project was undertaken by Fabbrica di San Pietro in collaboration with ENI as their technology partner. Records show that a faded colour emerged from under the grime. After consulting a 17th-century painting of the colourful facade and running extensive scientific tests at a lab in Milan, the team proceeded with the actual restoration process. They cleaned grime from the faces of stone angels, repaired cracks in the travertine, polished halos, and fixed mosaics. They put protective coats on the copper and iron and installed an electrostatic system to keep birds away from the facade.

2008- Mausoleum of the Valerii, the largest and most heavily decorated of the 22 family tombs in the Vatican necropolis, was restored in 2008 and opened to visitors soon after. Located under the central aisle of the Basilica, it also houses the tomb of St Peter. Dating to the second century AD, the Mausoleum features stucco decorations, which include family portraits and are described by experts as ‘of extraordinary value.

Over about ten months, the restoration team used the latest technology to work in the humid microclimate of the necropolis. They removed salty deposits from the decorations and set up a lighting system that shows off the tomb’s colours, sculptures, and reliefs. Charcoal ‘graffiti’ of designs and Latin inscriptions that were found were left untouched to allow for further research.

2011- Mosaics are among the most striking features of St. Peters Basilica. Several mosaics and tesserae were restored in 2011 by ‘St. Peter’s Mosaic Studio’ which was made responsible for the upkeep and maintenance of St. Peter’s mosaics. The consolidation technique used has been derived from fresco restoration and uses special glues that allow the damaged portions to be reattached to their bases. The process involves making small punctures between the tesserae (the mosaic stones) and then using syringes to fill the puncture holes with glue. Once the process is completed, the final cleaning of the surface takes place using ammonia salts, which give the tesserae its final touches. 

2016- During this year, a 4th-century wooden crucifix with an arm span of more than six feet was restored over fifteen months. Found behind an elevator shaft in a closed chapel before the restoration project began, the crucifix had been considerably damaged by termites, leaving bore holes peppering the face and body. The restorers filled the holes with wads of cloth, reinforced weakened areas with canvas wrappings and stucco, and hid dirt, discolouration, and black termite burrows with dark “bronze-coloured” paint. Using modern-day techniques, thermal lasers were used to blast off one layer of paint at a time and solvents that dissolve specific substances like oils, lacquers, and grime, leaving desired colours unaltered. The team also reported having monitored their progress with stereo microscopes to make sure they removed only selected areas and layers of the artwork.

Restored crucifix _©clay banks

2020– while the entire world was drenched in news concerning the covid pandemic, the Vatican commissioned four years of work to restore the aesthetics and safety elements of the bricks in the dome of the Saint Peter’s Basilica. The stone surface of the basilica has degraded over the years due to pollution and gases, which are reported to have been particularly harmful to the porous stone surface of the basilica. Given the advancement in technology, the project includes diagnostic examinations and the creation of a scan through laser equipment, which are expected to help better understand the sophisticated architectural structure designed by Michelangelo and Giacomo Della Porta.

Although several parts of St. Peter’s Basilica still need to be restored, the ongoing efforts at conserving its original magnificence stand testimony to the intention behind the effort are about replaceability as much as it is about the preservation of culture. Driven by a desire to save historic masterpieces, the restoration teams adopt methods that fix the damage, whilst ensuring that the original artistry of the works is not compromised, further allowing access to the historic glory by future generations. 


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Tara is a student of architecture, with a keen interest in exploring futuristic solutions for problems related to the built environment. As a budding writer and researcher, she looks forward to a future marked by harmony between the built environment and nature, marking the age of ‘ecological building’