On Monday, May 20, 29 eager Augustana College students and I will board a plane in Chicago and depart for Rome, where we will spend 12 days visiting various sites and meeting with church officials and others.
One of my favorite buildings in Rome is the Pantheon, the only building from ancient Rome that is still being used.
The Pantheon is one of the most fascinating buildings ever constructed. The dome is a perfect hemisphere made of unreinforced concrete resting on a perfect concrete cylinder with walls nearly 20 feet thick. There are no windows — the walls are too thick for that. There's only an oculus, an opening 30 feet in diameter at the highest point of the concrete dome.
The dome is a superb example of Roman mastery of concrete. While the interior of the dome is a perfect hemisphere, the exterior is not. The concrete was poured in layers over temporary wooden forms, and the lower layers are much thicker than the upper layers.
The Romans used various types of concrete. The lower layers of the dome are made of a heavier type of concrete that provided greater structural support. For the upper layers, the builders of the Pantheon used a lighter form of concrete, mixing in pumice, a porous volcanic stone, to lessen the weight of the concrete.
The weight of the dome is also lessened by five rows of coffers (recessed panels) that maintained the structural strength of the dome while reducing its weight. The five rows of coffers are also aesthetically very pleasing, a prime example of art and engineering joining forces.
What is most impressive about the dome, however, is that it is still structurally sound, having withstood numerous earthquakes without suffering any damage. All of this is quite remarkable because, as noted, the dome is of unreinforced concrete without any steel or iron bars to give it greater strength.
It originally was a temple dedicated to all the gods (hence the name), and construction of the first Pantheon commenced in 27 B.C. under the direction of Marcus Agrippa, who was Emperor Caesar Augustus’s son-in-law. The original Pantheon was seriously damaged by a huge fire in 80 A.D. but was rebuilt by the Emperor Domitian. The rebuilt Pantheon was also destroyed in a fire (fires were quite frequent in Ancient Rome).
Under the direction of Emperor Hadrian in the early second century, the Pantheon was once again rebuilt and assumed its present dimensions. In an act of generosity, Hadrian insisted that the name of Marcus Agrippa be inscribed on the portico even though the building he had constructed no longer existed.
In front of the Pantheon is very pleasant piazza (plaza) with a water fountain topped by one of the Egyptian obelisks stolen from their rightful owners by plundering Romans during the days of the empire. (While the Italian government has demanded that statues and other items from Ancient Rome in museums throughout the world be returned to Italy, the government has not offered to return the Egyptian obelisks to their rightful owners.)
In 609 A.D., several centuries after the Pantheon was built, the Byzantine Emperor Phocas, who was based in Constantinople, gave the Pantheon to Pope Boniface IV, who converted it to a church dedicated to St. Mary and the martyrs. It then became known as the church of Santa Maria Rotondo (St. Mary in the Round.) Just about everyone today, however, refers to the Pantheon by its original name.
The designation of the building as a church probably did save it from being dismantled to provide building materials for other buildings, a fate suffered by many other buildings from antiquity.
That’s not to say that no liberties were taken with the Pantheon. The bronze that once lined the ceiling of the portico was removed and melted down to make cannon for Castel Sant’Angelo and to make the swirling columns and the canopy of the high altar in St. Peter’s Basilica.
But for the most part, the Pantheon has survived intact, which is more than can be said of any of the other buildings of ancient Rome. That is what makes the Pantheon such a fascinating place to visit.