The Pantheon of Rome: A window into ancient Roman architecture


The majestic Roman Pantheon seen from Piazza della Rotonda.
Ron Current
Ron Current

As you enter the Piazza della Rotonda and first see the Pantheon what comes to mind is how good it looks. Unlike the other ancient structures in Rome, like the Colosseum and those in the Forum, that are in ruin the Pantheon looks as if it successfully survived the ravages of man and time over its almost two thousand year history. That’s because the Pantheon is the best preserved building from ancient Rome. So why was it built and how did it survive the destruction that befell the other Roman monuments?  What is the history behind this magnificent and breathtaking structure?

Sunlight streaming into the Pantheon’s rotunda from the Oculus at the top of its dome

Roman legend says that the first temple built on that site was to Rome’s mythical founder Romulus, however most historians’ now agree that the first Pantheon was constructed by Emperor Augustus’s right hand, Marcus Vipsanius Aprippa, in 27 AD. That temple burned in 80 AD, followed by a second temple constructed by Emperor Domitian. This building also was destroyed by fire after being struck by lightning in 110 AD. The Emperor Hadrian began the reconstruction on what is the current Pantheon in 120 AD, with the Greek architect Apollodorus of Damascus, and completed it in 125 AD. Hadrian is known for rededicating buildings and monuments that he rebuilt or repaired after the original dedicator, this is why the name on the facade reads: M. AGRIPPA L.F. COS TERTIUM FECIT (Marcus Agrippa, son of Lucius, the three-time consul, made this). This facade is the only portion of the original structure remaining of the 80 AD Pantheon.

What does the name Pantheon mean? Records do not specifically state to what god the temple was built for, but the name Pantheon in Greek means, “Honor all gods.” A theory is that it was the place that the Emperors could go to make public appearances that would reinforce their divine status to the citizens. On April 21st, the date that ancient Romans consider as the founding of Rome, an amazing lighting effect occurs.  When the midday sun hits a metal grille above the door it causes light to radiate out into the courtyard. Picture the Emperor standing in the door with all the light streaming around him from inside the Pantheon; they would look like a god.

The wondrous design and color of the interior rotunda.

How did the Pantheon survive what happened to the other buildings in Rome through time, that suffered from neglect and their materials reused for other buildings.  The Pantheon very well would have gone the same way if not in 609 AD, the Byzantine emperor Phocas gave the Pantheon to Pope Boniface IV who consecrated it as a Christian church: the Church of Mary and all the Martyr Saints, as it is still known today. This saved the Pantheon from being abandoned and ripped apart. The only losses to it were the sculptures that adorned the pediment above the front door and also Pope Urban VIII took all the bronze from the Pantheon’s dome and melted it down to be recast into canons. Another reason that helped preserve the Pantheon is that it was later also used as a tomb for the famous and the noble. The artist Raphael and several Italian Kings and poets are entombed there.

The Oculus at the center of the Pantheon dome.

The Pantheon may be one of the first Roman buildings whose interior is more glorious than its exterior.  As you enter through the two giant bronze doors you’re told that although these doors are ancient they are not the originals, those have been lost.  Now you are in the most amazing aspect of the Pantheon, its rotunda. As I walked in what awed me was the shaft of light coming into the rotunda from the hole at top of its dome (I snapped a photo as I entered, which is the one near the top of this post).

This hole, that is open to the sky, is almost 29 feet in diameter and is called a Oculus (sky), and is the only source of light inside the rotunda. Even with this sizable hole in its roof rain very seldom falls in and if it does the floor is slanted to drain the water.

You learn that the rotunda is a perfect hemisphere, where the diameter of the room is the same as the maximum height of the dome itself. This breathtaking dome is made of concert and was covered in bronze on its exterior, this is what was removed by Pope Urban VIII. The Pantheon’s dome was the largest in the world for over 1,300 years. It still holds the record as the largest unsupported dome. Although it doesn’t look like it it’s larger the dome of St. Peter’s basilica. Comparing it to our U.S. Capitol’s, which is 96 feet in diameter, the Pantheon’s is much larger at 142 feet. It’s an amazing architectural feat done by the Roman engineers, who lighted the weight of the dome by progressively decreasing the thickness of the its walls and creating internal spaces within those walls.

M. AGRIPPA L.F. COS TERTIUM FECIT (Marcus Agrippa, son of Lucius, the three-time consul, made this).

Everything about the Pantheon is amazing. The columns supporting the portico came from Egypt and weigh 60 tons each. They are 39 feet tall and 5 feet in diameter.

The Pantheon is not only the most perfectly preserved building from the ancient Roman period,  it is also with its magnificent dome and interior design a perfect example of the skills of Roman architects and engineers.

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