Hadrian’s Pantheon: the link between heaven and earth

"The Pantheon [was] the first great monument of non-useful architecture” (Meeks, 135).

The Pantheon is iconic. It has inspired architects worldwide. As Meeks says, it is undoubtedly a great monument. But the question remains—did the Emperor Hadrian have a reason to build something so grand and imposing, something so unnecessarily out of the ordinary? Was it truly “non-useful” architecture?

Hadrian had been named emperor under more than questionable circumstances. Some say he faked his adoption by the previous emperor, Trajan, after Trajan had already expired. Some said he rose to power through manipulation of Trajan’s wife. Hadrian was a skilled orator and would often write speeches for Trajan, so it’s known that they worked together. Records indicate that they were on good terms, but rumors still circulated amongst the Romans. And, after being named emperor in 117 AD, he didn’t return to Rome immediately to assume his position but rather stayed in Syria for a year, raising further questions for the Roman population. So perhaps he did have a reason to undertake such an impressive building project—he needed to regain the respect and acceptance of both the Senate and the people of Rome. What better way to do this than to construct a very large and imposing monument? Hadrian did initiate a grand building plan soon after he became emperor and the Pantheon was a part of that plan.

Perhaps he just wanted something daunting that he could govern the world from. Perhaps he wanted to appease the gods who had “destroyed” the previous two Pantheons. Marcus Agrippa (the son-in-law of Augustus) had originally built the first version of the Pantheon in about 25 BC but it burned down in 80 AD. His Pantheon was in the same spot as the one we know today but was much smaller and rectangular, bearing no resemblance to what we see now. Agrippa’s Pantheon was rebuilt under Domitian, only to promptly be struck by lightning and burn down again during Trajan’s reign. Maybe Hadrian took the lightning as a threatening sign from the gods, saying that if he were to rebuild it, it had better be completely different from the previous ones.

Figure 1: Agrippa’s Pantheon (gray) superimposed with Hadrian’s (white)

Regardless of the reason, Hadrian thus commissioned one of the most iconic edifices in history. Although little is known about the architect or the actual construction of the Pantheon (Hadrian himself may have designed it), the building process is thought to have been started in about 120 AD. It resulted in a massive structure with the largest unreinforced concrete dome in the world.

The dome itself is a marvel of engineering. Concrete, the building material, does not have a very high tolerance for stress so is reinforced with steel in modern buildings. In Roman times, they didn’t have steel so the dome is pure, unreinforced concrete and stretches a remarkable 43.3 meters in diameter. The Romans intelligently designed the top of the dome to be less dense than the bottom which put less stress on the building and allowed it to stand for nearly 2,000 years. The concrete used at the top of the dome is made mostly of basalt and has many air spaces, making it much lighter than the tufa-rich concrete used toward the base of the dome. The interior of the dome was originally gilded with bronze, which would have beautifully reflected the light shining in from the oculus. However, that was stripped away centuries ago.

The dome rests on a cylindrical base also 43.3 meters in diameter and together they make up the rotunda. The height from the floor to the oculus is again 43.3 meters. The symmetry this creates would allow you to either house the rotunda in a 43.3 meter cube or house a 43.3 meter diameter sphere within in the rotunda, pointing to the interplay of circles and squares present throughout the Pantheon. The oculus (the hole in the center of the dome) is the main source of light in the building and is about 9 meters across. It was obviously an intentional hole in the roof because it necessitated an expensive drainage system in the floors.

Observing the inside of the dome, one can see the square coffering carved into the concrete. These coffers serve no structural purpose but the meaning perhaps lies in the number—there are 28 squares in each ring and there are also 28 days in the lunar calendar. If Hadrian’s Pantheon was intended to appease the celestial gods after they struck down the previous two, homage to the moon would have been necessary. The large oculus, the source of light, could then symbolize the sun by opening to the heavens, tying the earthly building to the sky above.

Figure 2: Rings of rectangular coffers on the Pantheon ceiling

The coffers are also arranged in five rings circling the dome. This again brings the union of the circle and the square to our attention.

Shifting our view to the floor, circles and squares are found together again. The pattern in the marble flooring is of circles inscribed in squares.

Figure 3: The floor of the Pantheon, with the circle and square pattern in the marble

Inside the rotunda itself, there are seven alternating circular and rectangular niches (more of the circle-square interplay). The eight additional small niches, combined with the seven large ones, along with the door, divide the building into sixteen sections, thought to correspond with the sixteen sections of the Etruscan sky. This sky sent the lightning that destroyed the previous Pantheon and thus honoring the celestial gods was a smart move on Hadrian’s part. It would not only appease the gods for whatever the original Pantheon had “done wrong” but would also generate support from the believing, religious Roman population, necessary for Hadrian who started his reign as an unpopular emperor.

The orientation of the larger niches also provides an axis within the cylindrical building, giving the circular interior a “front” and a “back”, like a standard rectangular building would have. Even the outside of the building, with the rectangular section connecting the massive portico and the cylindrical rotunda continues the union of circles and squares.

Figure 4: The cylindrical rotunda in contrast to the rectangular section joining it to the portico

The portico in itself is impressive with its three rows of columns, eight in the front row and four in the two behind, totaling sixteen massive 60-ton columns. Here, sixteen appears again, corresponding again with the sixteen sections of the sky. Walking through the columns brings you to the large doors (although not the original doors to the building) which give the Pantheon a daunting, impressive façade. In ancient times, there would have been stairs leading up to the portico, making it all the more imposing. It is also somewhat surprising to note that the inscription on the front of the portico gives credit to Agrippa for building the Pantheon, not to Hadrian who was actually responsible. However, the previous two attempts at this building had been struck down by the gods, so perhaps Hadrian didn’t want to attach his name to something that might continue the streak of bad luck.

Figure 5: The massive columns of the portico along with part of the inscription crediting the construction to Agrippa

Regardless of the inscription, the union of the circle and the square (or their three-dimensional counterparts, the sphere and the cube) seen throughout the structure was perhaps used by Hadrian to connect himself with the gods. The Romans (as do many other cultures) thought of the circle as the ideal shape, often linked to the sun or the gods. It represents perfection, which gods are theoretically the only ones to obtain. The square, on the other hand, was often used to represent the physical, earthly world which the Romans were a part of. The constant interplay of the two shapes could be Hadrian’s attempt at uniting himself and his empire, represented by the square, with the heavens and gods above, represented by the circle. Hadrian thought very highly of himself. At his birth, it was prophesized by his grand-uncle that he would one day “rule the world” and because that came true, he thought he’d surely attain god-status. “Indeed no matter what the Roman Senate thought, Hadrian would become a god after his death because he had been one since birth” (Joost-Gaugier, 35). If Hadrian wanted to immortalize himself in his structure, linking the gods and the earth would be a good place to start.

Other than cementing his connection to the celestial gods with his massive structure, there is still some controversy over what Hadrian actually used it for. Some say the Pantheon was a temple to the Roman gods (after all, the name Pantheon means “all gods”). However, it is typically thought that Hadrian used it as an audience hall, a public place from which he could preside over the people in all his glory. According to Dio Cassius, writing a history of Rome around the turn of the second century, “Hadrian held court with the assistance of the foremost men, now in the Palace, now in the Forum or the Pantheon or various other places, always being seated on a tribunal so that whatever was done was made public” (McEwen, 57). He may have made public announcements or administered his policies of justice from his seat in the Pantheon. With the light from the oculus shining down upon him and the grand entryway leading up to the Pantheon, Hadrian must have seemed on par with the gods, justifying the building’s role as an audience hall. However, he was gone for twelve of the 21 years he was emperor on a quest to explore and define the borders of his territories, so perhaps he didn’t spend much time in the Pantheon and it had yet another use altogether.

Although Hadrian’s use is still unclear, the Pantheon began to serve as a church after the seventh century when it was cleared of its “pagan filth” and converted to honor the Virgin Mary and her martyrs. Pope Boniface IV was responsible for this conversion in 609 which ultimately saved the ancient building from destruction or abandonment. It began to be used as a tomb during the Renaissance and currently Raphael, the painter, and Vittorio Emanuele II and Umberto I, two kings of Italy, are buried there. Today, it is still used as a church and is one of the oldest buildings in the world still in use.

The Pantheon has been standing for almost 2,000 years and is still a solid, monumental piece of engineering. Although Hadrian may have built it to look imposing, people today can’t help but be in awe of its stunning size and beauty. It still looks imposing, that’s for sure, especially when one considers the fact that it’s been standing there for longer than we can really fathom. Hadrian accomplished a beautiful juxtaposition of straight lines and curves that has been mimicked worldwide, from the Panthéon in Paris, to numerous churches, like the Assumption Church in Poland, to a number of other structures.

Figure 6: The Panthéon in Paris, France is strikingly similar to Hadrian’s original

We still look to the Pantheon as a source of inspiration for our modern architecture. We still marvel at the fact that all the concrete stands, unreinforced, and that it hasn’t significantly deteriorated or collapsed. The Pantheon still fascinates both the tourist and the true Roman and should continue to do so for centuries to come. It fascinated me when I was researching it. I didn’t realize that there was so much symbolism behind it, from the combination of the circle and the square to the numerical symbolism it is speculated to have. It was built in a way to surprise you—walking in, I didn’t expect to see the dome in all its glory or the oculus lighting up the entire building. From the outside, it looks incredible but didn’t really seem spectacular in any way until I went inside. It’s not just a building but seems to me truly a work of art. I don’t think it is “unnecessary architecture” in any way, as Meeks stated, because walking inside definitely left me stunned and wanting to go back.

Figure 7: Me, thinking the Pantheon is awesome!

Bibliography

Hutchinson, P and Mark, R. “On the Structure of the Roman Pantheon.” The Art Bulletin. 68. 1 (1986): 24-34.

Joost-Gaugier, C L. “The Iconography of Sacred Space: A Suggested Reading of the Meaning of the Roman Pantheon.” Artibus et Historiae. 19. 38 (1998): 21-42.

Marder, T A. “Bernini and Alexander VII: Criticism and Praise of the Pantheon in the Seventeenth Century.” The Art Bulletin. 71. 4 (1989): 628-645.

McEwen, I K. “Hadrian’s Rhetoric I: The Pantheon.” RES: Anthropology and Aesthetics. 24 (1993): 55-66.

Meeks, C L V. ”Pantheon Paradigm.” The Journal of the Society of Architectural Historians. 19. 4 (1960): 135-144.