The Pantheon: why it still inspires modern architecture?

Hi everyone and welcome back to Exploring Art, this is Alessandro. I am sure you know this monument, the Pantheon in Rome. An ancient, really ancient, former Roman temple that survived to invasions and devastation, then catholic church and now one of the most visited attractions.

And no matter how many times you have visited it, the Pantheon is always a surprise and today we are going to understand why, starting with something evident like the dome (that has been the largest in the world for almost 1,400 years) and then going deeper in its amazing features, tons of fun facts and talking also about what is still unknown and the architects who got inspired by it through its long history.

Pantheon Rome side
NAME Pantheon
YEAR from 27 BC – 14 AD to 125-128 AD
TYPE Architecture
DIMENSIONS dome 43,4 m (142 ft)
MATERIAL Bricks and marble

Pantheon: 2000 years of history

I know it seems impossible, but the Pantheon is almost 2,000 years old. It is in fact one of the best preserved ancient Roman monuments. But, before telling you how it survived in such a good shape, let’s make a step back in history to understand its importance and here we have already some surprises.

Most textbooks and online resources date the building to the Emperor Hadrian’s reign from 117 to 138 AD and describe its purpose as a temple to all the gods (the name in fact is from the Greek pan = all, theos = gods). However, thanks to new pieces of evidence and discoveries, some scholars argue that these theories are wrong and the origins are way different.

To make things even more complicated is the inscription on the frieze that identifies, in abbreviated Latin, Marcus Agrippa as the patron: “M[arcus] Agrippa L[ucii] F[ilius] Co[n]s[ul] Tertium Fecit”. Clear right? JK, it means “Marcus Agrippa, son of Lucius, thrice Consul, built this”.

Who want it?

Marcus Agrippa was a Roman general and consul (the highest elected official of the Roman Republic), but also architect, close friend, son-in-law, and lieutenant to the first Roman emperor Augustus. That means he was one of the most influent, rich and important persons in the Empire.

Unfortunately, he lived in the first century BC, so why is there his name on a temple built one century after?

Before answering remember that if you struggle with BC, AD, CE, BCE, click here to understand the meaning and how to use them. 

What happened is that Agrippa built an earlier temple between 27 BC – 14 AD which had burned down except, it seems, for the façade.

The building was lately reconstructed keeping the same structure and dimensions. However, another fire partially destroyed it around 110 AD (I know, not the best luck), but the Romans were stubborn and rebuilt it beginning around 114 during Emperor Trajan’s reign. The evidence of that is on the bricks used in the building’s construction. Some of them in fact were stamped with identifying marks that can be used to establish the date of manufacture and, almost all of them, date from the 110s.

The building was just completed under Hadrian around sometime between 125 and 128.

Julius Caesar - Hadrian birth and death - BC vs BCE - AD vs CE explained
Julius Caesar and Hadrian birth and death

Why Pantheon?

Ok, now we have the dates. But what was it? Like I said before, the name Pantheon means a temple dedicated to all the gods. However, there is an important document written by Cassius Dio, an historian and Roman consul who lived a century after the building was completed, and he says that “Pantheon” was mostly a nick name or because it was decorated with the statues of many gods or “because of its vaulted roof, it resembles the heavens.”

It seems in fact that it may have been intended as a dynastic sanctuary, part of a ruler cult emerging around Augustus as member of Julius Caesar’s family and back to Romulus, Rome’s mythic founder.

That would change completely the meaning of the monument.

Pantheon Floor-plan
Pantheon Floor-plan

Pantheon features

Let’s see now the Pantheon features. The design is simple as we can see from the floor-plan: there is a portico with free-standing columns and then a domed rotunda. The two elements are connected by an intermediate block.

However, even in its apparently simplicity the result is majestic and powerful already looking at the portico where we can identify a frieze and a pediment and of course the huge columns with Corinthian capitals (we learned a lot about these elements in the previous videos – check in the description if you missed them).

Some fun facts about the columns. They have been replaced in the centuries with copies of less fancy materials, but all the 16 of them were monolithic Egyptian granite. In other words, they were a single piece of granite quarried in Egypt and transported to Rome after thousands of miles.

And just to give you some numbers: each column is 60 tones in weight, 11.9 meters (39 ft) tall, 1.5 meters (4 ft 11 in) in diameter. Try to imagine what it meant moving them with their technology. Another detail: the 8 in the front are grey and the two groups of 4 are pink.

Even the capitals are huge: 2.4 meters (7 ft 10 in) tall.

An important thing to say is that today the Pantheon is surrounded by houses and we can reach it from different directions. Back to the Roman empire the only way to reach the entrance was from the front since there was a big closed square that made the visual effect even more majestic than today since Piazza della Rotonda is significantly smaller.

The Pantheon inside: static movement

However, the impact is still extraordinary and, after passing the oldest large bronze doors in Rome measuring 4.45 meters (14.6 ft) wide by 7.53 meters (24.7 ft) high (yes even for that the Pantheon has a record), the space opens up in a way that we couldn’t imagine.

There is a vast circular space with a huge dome that fills completely the field of vision and gives a disorienting feeling. The reason is that usually a dome stands on a higher drum like we learned in the Dome of Santa Maria del Fiore video. Here instead look what the Roman architects designed: the internal space is so geometrically perfect to accommodate a perfect sphere. As a consequence, we fill like we are inside a bubble and this determination of researching perfection is clear on the use of the two most perfect geometrical figures: circles and squares. They are present on the ancient marbles on the floor, on the side decorations and even on the concentric circles of square coffers in the dome. And guess what: even their number has a specific meaning. They are in fact in five rings of 28. 28 was considered a perfect number by romans: a whole number whose summed factors equal it (1 + 2 + 4 + 7 + 14 = 28).

The sunken panels create also the effect of a pulsing, dynamic, dome. And this effect is amplified thanks to another trick. If we look at the columns we can notice that they are perfectly aligned to the frieze decorated with false windows, but they are not aligned with the coffers. That amplifies even more the dynamism inside this unique space.

Pantheon inside - dome
Pantheon inside - dome

Pantheon deep secret: concrete

And be careful because the marble visible on the inside is just a decoration covering the real material that gives the strength to this huge building: concrete.

Exactly: the simple, cheap concrete combined to bricks, a technique that the Romans perfected becoming masters. The drum wall is 6.4-meter-thick (21 ft) and it was the only way to support the downward thrust of the 4,535 tons dome.

Super heavy because even the dome is made entirely of concrete and here another record since it is the world’s largest unreinforced concrete dome.

And let me show you the genius of the Roman architects. Not only the dome thickness varies from 6.4 meters (21 ft) at the base of the dome to 1.2 meters (3.9 ft) at the top, but also the materials are different. At its thickest point, the aggregate is travertine, then terracotta tiles, then, at the very top, tufa and pumice, both porous stones that make the top lighter reducing the risk of collapse.

The dome

And we finally reach the top where we can see the fascinating oculus. And you may wonder, why a hole in the dome? Well it’s the only light that comes into the space with the exception of some light wells on the sides and the door of course. The sunbeam streaming through the oculus trace an ever-changing daily path across the wall and floor of the rotunda and that helps the idea of the movement inside the monument as well.

And no, there is not glass: the oculus is completely opened, so, when it rains, the floor gets wet. Probably now you can expect even the oculus to be huge: it is 9 meters (29 ft 6 in) in diameter.

Another fun fact: before I said the Pantheon is the world’s largest unreinforced concrete dome. Not only: with 43,4 meters (142 ft) in diameter it has been the largest dome in the world for 1,400 years until Brunelleschi built the extraordinary dome of Santa Maria del Fiore in Florence. You should watch the video if you missed it because that building is still something unbelievable since experts are still trying to figure out how he was able to create it.

And, like Brunelleschi, during the centuries the Pantheon inspired many other architects starting with Palladio, Thomas Jefferson, Charles Follen McKim, Wallot and so on.

From temple to church

And if we are still astonished today, try to think how the Pantheon would have looked like with all its decorations. The pediment was decorated with relief sculptures, probably of gilded bronze. Even the external marbles have been removed over the centuries. All the statues inside and outside got lost and many columns and materials have been replaced with cheaper versions. And covered of gilded bronze were also the coffers inside the dome and we cannot even imagine the visual effect.

Considering all of that, plus earthquakes, wars, invasions, how was possible for the Pantheon to survive? Well in 609 it was converted into a Christian church and the consecration saved it from the abandonment, destruction and the spoliation that happened to the majority of ancient Rome’s buildings.

However, the Church took also questionable decisions. In particular in the early 17th century, Pope Urban VIII tore away the bronze ceiling of the portico, the last bronze that survived, and, if that brilliant idea was not enough, he replaced the medieval campanile with the famous twin towers which were not removed until the late 19th century.

Why did he need the bronze? To allow Bernini to build the beautiful St. Peter’s Baldachin. But this is another story.

Baldacchino St. Peter - Bernini
Bernini - St. Peter's Baldachin


So, the Pantheon is really full of surprises collected during its long history and there are still many others that are waiting to be discovered. And I bet that from today you will look at this monument from a completely different perspective, in particular considering it is a building almost 2,000 years old.

And, if you have the opportunity to visit it, remember to pay tribute to one of the greatest artists: Raffaello who is buried inside this piece of history and culture.

Thanks for reading. Give a look to my social media for more info and pictures. All the links in the description. Ciao!

Share with your friends

Leave a Reply