An Analysis of the Architecture of St Peter’s Basilica!

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St. Peter’s Basilica is the most beautiful church in the world, crafted using insights from the twelve best Renaissance architects!

Its architectural brilliance and unique look attract over ten million visitors annually, mainly because of its magnificent towering dome.

Architecture lovers and first-time visitors planning to explore the Basilica must discover some architectural features that make it a marvel.

In this article, we’ll discuss the foundation and the current architecture of St. Peter’s Basilica and learn more about what inspired the look of this marvelous sacred space! 

The Dimensions & Architecture of St. Peter’s Basilica 

The Basilica is currently 150 meters wide and 220 meters long.

It has the tallest dome in the world, standing at a height of 137 meters (448 feet) from the ground to the tip. 

St. Peter’s Basilica is in the Baroque style of architecture, which got its dome inspiration from the Roman Pantheon.

It lies in a Greek Cross base formation, and the dome is supported only by a few pillars, unlike the Pantheon’s continuous supporting wall.

Before this modern Basilica structure was constructed, the Old St Peter’s Basilica Architecture acted as the base and stood in the same spot built in 349 AD.

The construction of the Basilica structure you see today began in 1506, and it took around 120 years to complete the construction.

The time was spent reconstructing a few elements because of clashing design ideas from the twelve architects.

Over the years, many additional altars, chapels, and sculptures have been added to the Basilica, which only continued to increase its beauty.

It has now become a famous symbol of Renaissance architecture in Rome.

The Twelve Architects who designed the St. Peter’s Basilica

Pope Julius hired Italy’s best architects to create the biggest and most magnificent church in the holy Vatican City.

He held an exciting design competition to select the leading architect for this Vatican masterpiece.

Donato Bramante won the competition, as his Greek Cross formation and Pantheon-like Dome caught the eye of the Pope the most.

Even though the layout was originally a Greek Cross, Carlo Maderna finally decided on a Latin Cross, which is what you see today.

His design also included a unique roof lantern addition at the top, similar to the Florence Cathedral’s design. 

You can still see the sketches of the other participants displayed in the Uffizi Gallery.

Bramante definitely could not do all the work by himself, and he received help from many other famous architects who helped perfect the design of the Basilica you see today!  

Giuliano da Sangllo and Fra Giocondo took over the construction work after Bramante’s death, followed by Raphael’s involvement and redesign. 

Check out the table below for a quick glance at what each of the twelve architects contributed to the Basilica’s construction. 

ArchitectArchitectural elements worked on
Michelangelo Buonarotti The Dome and other foundational elements. 
Donato BramanteGreek Cross floor plan with a Dome structure like the Pantheon and an added lantern at the top.
Fra Giocondo Worked on constructing Bramante’s ideas. 
Raphael SanzioCreated different Chapel rooms and defined the square exterior walls and the interior semi-circular apses. New Latin Cross plan.
Baldassare PeruzziReverted to the Greek Cross floor plan and worked on Raphael’s design changes. 
Antonio SangalloExtending the Basilica into a short nave with a wide portico area.
Giacomo della PortaMade a few changes to Michelangelo’s Dome design with Domenico Fontana. 
Domenico FontanaCompleted Dome on Michelangelo’s instructions in 1590 with Giacomo della Porta. 
Diacomo Da VignolaSide Cupola construction. 
Carlo MadernaExtended the central Nave to create a Latin Cross. Designed the Facade and the atrium. 
Gian Lorenzo BerniniAdded Noble Entrance Plaza and the Baldacchino. Completed the Latin Cross plan.
Giuliano da SangalloContinued construction on Bramante’s designs. 

Early Constructions

When Bramante began working on the construction in 1506, he began constructing the interior first, allowing him to try out different shapes for the Basilica.

He showed the workers the design by building a wood or clay model for them to follow.

Raphael took over the construction command in 1514; he provided a ground plan view in three ways, clearly showing the construction from all angles. 

Let’s take a look at the construction of the foundational elements of the Basilica! 

The Piers & Barrel Vaults 

To construct the massive 45-foot-tall pillars of the Basilica, Bramante ordered that 25-foot-deep trenches be dug.

The Piers were constructed between 1507 and 1510 when Bramante added 150-foot tall coffered barrel vaults to join the pillars.

Each of the four piers was topped off with a Corinthian capital of six feet, with many gaps in the middle to keep the core space open.

This was the first massive formation to be built all over the world!

Sadly, the piers were not strong enough at the beginning, but Antonio da Sangallo and Michelangelo later worked on them.

Michelangelo decided to make each pier thicker and leave less space between them, which made the whole foundation strong! 

The Floor of the Basilica

Antonio da Sangallo worked on the Basilica’s floor and raised it by 12.5 feet from Bramante’s original design.

He feared the Basilica would sink into the marshy surrounding land, so he decided to make these changes. 

Antonio continued to add thick parallel walls seventeen feet apart and connected by vaults to support the heightened floor.

He also ensured that the piers were strong enough to hold up all this weight. 

The Dome

The dome is one of the most unique architectural constructions in St. Peter’s Basilica, whose design began in 1574 under Giacomo della Porta. 

Its construction was completed in 1590 and took around 22 months to complete from scratch. 

Bramante’s original design of the Dome included a hollow Pantheon-like single outer shell with a saucer-shaped design.

But when Bramante died, Antino Sangallo took over and changed the design to a three-tiered structure.

When Michelangelo was appointed as the head architect in 1546, he changed the structure again to create a round dome that you see even today. 

His design included a ribbed structure with two shells and open windows in the cupola and drum area.

This double shell covering worked splendidly in protecting the Dome from harsh weather. 

When Dominico Fortana and Giacomo della Porta took over the construction after Michelangelo, Porta changed the outer shell into a sphere-elongated dome shape.

The typical Renaissance herringbone pattern, which included placing bricks in an inverted V shape, was used on the dome. 

Three iron hoops are also added to the dome for additional support and push against the circle of the dome. 

Thin slabs of travertine with lead coating were also added to the cupola. 

St Peter’s Basilica Architectural Features 

Now that you have seen the foundational architecture of the Basilica let’s take a look at the construction of all the decorating elements!

Each element has a unique look that makes it so special.  

The Facade

Carlo Maderno designed the 119-meter facade, standing independently from the entire Basilica area.

It is made entirely of Travertine stone and has massive Corinthian columns with a raised central pediment.

Behind the pediment is an attic, a Greek-style wall above the facade, with a massive statue of Christ behind it.

Jesus is standing beside eleven of his Apostles, excluding St. Peter, who stands on the left side of the staircase. 

At the base of this attic is an inscription honoring Pope Paul V in 1612.  

The Atrium

Carlo Maderna designed the Atrium, which is 71 meters long and 13 meters wide, which is the grand entrance of the Basilica. 

Ancient medallions and other artifacts line the span of the atrium, which is a must-see! 

Entrance areas

St. Peter’s Basilica has five different entrances, from the atrium area to the chapel, with all bronze doors. 

Most visitors enter the Basilica through the main entrance door on the portico or from the shortcut door on the right side of the Sistine Chapel.

Besides the Bronze Door, which is opened on the first day of every jubilee year, all other entrances are usually always closed to the public. 

The names of some of the other doors are the Door of Good and Evil, the Door of Sacraments, and the Door of Death. 


The Basilica has around 25 altars in total, but the Papal Altar, reserved only for the Pope’s use, is the most famous.

It stands at the center of the Basilica, over which towers the Baldacchino canopy by Bernini.

St. Peter’s tomb is believed to be placed directly under this altar. 

The Nave

The Nave by Carlo Maderno is created so that even though its axis is slightly tilted, it perfectly aligns with the St. Peter’s Square obelisk!

Maderno added fake columns to the nave to imitate Michelangelo’s original nave.

On the central nave by Michelangelo, you can see inscriptions written to praise the Catholics and St. Peter.

The nave also has massive stoups to carry holy water, with angels almost 2 meters high on either side.

It divided the Basilica into eleven chapels, which you can read about ahead! 


The Basilica has eleven chapels, divided by the massive nave, each with masterpiece artwork, stucco, and other decorative elements.

These also include the chapels that surround the Dome!

The most visited chapel is the Chapel of La Pieta, housing the marble masterpiece sculpture of Mother Mary cradling the body of Jesus after his crucifixion.

The other chapels are dedicated to saints and include the entrance to the Sacristy and the other Church altars. 

Sculpture Additions 

You will see some of the most brilliantly crafted sacred sculptures from the Renaissance period inside the Basilica.

Designed by famous art masters, including Bernini, Michelangelo, and others, the Basilica’s collection has become the most attractive in the Vatican City.

You can see gigantic Pope sculptures, the famous bronze statue of St. Peter, and the Michelangelo La Pieta sculpture inside the Basilica.

Check out our article on what to see inside St. Peter’s Basilica to discover all the beautiful artworks in the Basilica! 

Clocks and Bells on the Basilica’s exterior

From the outside, on the facade of St. Peter’s Basilica are two clocks, made to replace the bell towers Bernini constructed.

The clock on the left side shows the time in Rome, while the one on the right shows the European standard time.

You can also see three bells at the top of the Basilica from below, while the other three are behind the bourdan bell, weighing 9 tonnes!

The other bells are much lighter, beginning from 260 kgs.

The bourdon bell is rung during Christmas, Easter, the Saints Peter and Paul feast, and during the Urbi et Orbi blessing on Easter Monday.

Vatican Grotto Tombs

Below the Basilica is the Vatican Grotto area, housing the burial remains of 91 Popes, members of the Royal family, and other important citizens.

The walls are covered with stunning 4th-century fresco paintings, and you can also see other ancient artifacts inside the Grotto. 

What Materials were used to construct the St. Peter’s Basilica?

Travertine, a kind of lime-based material, was mostly used in the construction of the facade of St. Peter’s Basilica.

The large amounts of travertine used in the Basilica came from Tivoli and were transported over twenty miles.

Pope Julius disagreed with spending so much money on transportation and collection of the material.

Bramante was forced to use bricks and crushed tufa to the exterior.

Recycled material from other famous sites in Rome was also used in the construction, like the ancient Colosseum stones.

Broken columns and arches from the Palatine Hill were also recycled in St. Peter’s Basilica’s structure. 

Forty-four marble columns and most sculptures in the Basilica use pure white marble, like Michelangelo’s La Pieta. 

FAQs on the Architecture of St. Peter’s Basilica 

1. Who are the twelve architects of St. Peter’s Basilica?

The Twelve architects of St. Peter’s Basilica are:

  • Michelangelo Buonarotti 
  • Donato Bramante
  • Fra Giocondo 
  • Raphael Sanzio
  • Baldassare Peruzzi
  • Antonio Sangallo
  • Giacomo della Porta
  • Domenico Fontana
  • Diacomo Da Vignola
  • Carlo Maderna
  • Gian Lorenzo Bernini
  • Giuliano da Sangallo

2. What is the architecture of the Vatican Church?

The Vatican St. Peter’s Basilica has a Baroque style Renaissance architecture. The Roman Pantheon inspires its dome. 

3. What makes St. Peter’s Basilica unique?

St. Peter’s Basilica has the tallest dome in the world and is the biggest Church, standing at a height of 499 feet. 

4. Why is St. Peter’s Basilica considered a great piece of architecture?

 The Basilica boasts the best architecture in Vatican City, with its unique dome and majestic interiors. Its dome is the tallest existing dome in the world, standing at a shocking height of 449 feet. 

5. Who constructed the dome of St. Peter’s Basilica?

 Michelangelo designed the stunning dome of St. Peter’s Basilica. After Michelangelo’s death, Giacomo della Porta and Domenico Fontana later worked on its construction.

6. Who commissioned the Basilica?

Pope Julius commissioned the Basilica in 1506.

7. When was the Dome’s construction completed?

The construction of the Dome was completed in 1590. 

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