The Pantheon Flashcards
Discuss the 5 features that assured stability for the dome
The dome is made out of concrete. Its stability is assured by means of several features:
1) The concrete is thinner at the top, and thicker near the base.
2) The concrete near the oculus is of lighter than normal density, while that near the base is heavier. The Roman engineers achieved this by using variously lightweight volcanic stones, and heavy granite stones, as the aggregate in the concrete. Very similar methods are still used, particularly for lightweight concrete.
3) The bottom of the dome is made heavier by the use of brickwork built up on top of it, as a counterbalance.
4) The dome is lightened, while maintaining its stiffness or rigidity, by its ceiling being relieved or made thinner in rectangular sections, called coffering.
5) The oculus, as well as being a beautiful and unique feature to admit light, also reduces the weight of the dome.
What does the Pantheon show about the Emperor Hadrian?
The Emperor Hadrian travelled the lengths of the Empire and loved the diverse range of architecture in different provinces, which he brought back to Rome
The overriding impression is the power and victorious rule of the divinely ordained Roman emperor.
The association with the construction of the Pantheon which is dedicated to the gods further established Emperor’s divine links. Although the emperors did not need to be regarded as gods, they had to appear beyond the reach of any ordinary mortal, and so used architecture to convey themselves at the epitome of their power.
What was the Pantheon used for?
The original use of the Pantheon is somewhat unknown, except that is was classified as a temple. However, it is unknown as to how the people worshipped in the building, because the structure of the temple is so different from other traditional Roman temples.
The Pantheon was a vast space that served as a temple dedicated to the planetary gods, a spiritual place.
Size of the Pantheon
The sheer size of the Pantheon makes you feel small and insignificant compared to the gods. It also makes one feel powerless/subordinate against those in power.
The imposing nature of this building has the ability to impress and awe any passerby.
The Romans used large scale to show their dominance in the ancient world.
Used height and scale as a means of showing how powerful their political regime was.
The enormous size and scale of the Dome, along with the unbelievable Oculus → shows the wealth of Rome and its powerful and domineering standing in the ancient world
Dimensions - Dome width and height are the same (43.2m)
The dome and the oculus
The magnificence and height of the dome was unprecedented at that time in history. The effect is to bestow upon any visitor just how politically and culturally advanced the Roman Empire had become.
When you look through the oculus of the Pantheon, you feel as though you are being watched by the heavens. There was great propaganda value for doing this because it highlights an idea heavily expressed in ancient Rome; the idea that you are always being watched over by beings of higher power and status.
The light coming through the oculus relates to the movement of the heavens and celestial bodies. Lack of light at lower level drew attention to the oculus and thus the heavens.
The dome ceiling was likely painted blue with the gold rosettes serving as stars
The misalignment of the coffers and niches on the dome give a sense of rotation to the sky
The actual dome starts lower than appears on the outside.
Oculus lets light into the rotunda → As the sun moves across the sky it illuminates different parts of the interior creating a play of light and shadow.
Given the spherical conception of Hadrian’s Pantheon it is easily imaginable that it was dedicated to the planetary deities. The Orb was in fact a symbol of the world and the universe and consequently doubled up as a symbol of the Emperor’s power.
The Pantheon is a radial building which means that it has a central point and radiates outwards from that central point.
The oculus represents gods looking down upon humanity
The oculus was an engineering gem of the Roman world.
Materials used
Concrete → lighter than stone and is able to be shaped whilst giving the building strength and stability
Opus signum → crushed brick making the building stronger but also lighter. This was a very good material to use to combat the issue of the dome’s weight as it decreased the dome’s overall weight
Brick and travertine was used to fill the concrete at the bottom of the dome however lighter pumice was used to fill near the top
The granite for the column drums were sourced from Egypt. Hadrian, a Roman emperor and the individual who commissioned the Pantheon, liked to travel around his empire and to bring back foreign design and materials to Rome. This was not only done from a design perspective but it also showed off Rome’s wealth and power.
All of the materials beautify the building without adding extra weight to it. In most instances it is decreasing the weight.
The Pantheon used both local and imported materials with no expense spared depicting the power, wealth, ingenuity and far reaching influence of this empire. For example, the Pantheon had imported granite from Egypt for the column drums in a remarkable feat of logistics. The extravagant materials announced that these buildings were ‘status’ structures designed to impress.
The various colours of marble from different regions of the Empire and the enormous monolithic granite columns from Egypt → show off the wealth and power of the Empire
Originally the dome was a concrete core covered in bricks. The concrete was laid in progressively thinner layers as it went up to reduce the overall weight. Later made much stronger with the addition of opus signum and covered in a layer of bronze tiles
Engineering of the Pantheon
The Pantheon dome was made Opus signum so that there was less mass that the other weight carrying structures, such as the internal corridors and niches, had to support.
In the Pantheon there is a coffered roof on the dome which is used as a way to combat the engineering issue of weight distribution. Recessed coffers → in 5 rows, decreasing in size the closer they get to the opening. They were mainly a decorative feature, but also lessened the weight of the roof, while keeping the overall strength.
Marble veneer used higher up to lessen the weight.
The height of the interior is the same as the width (43.2m). A sphere would fit perfectly inside.
The problem of the mass of concrete drying was overcome by having semicircular voids in the wall behind the eight ground level niches
The circular and square shapes in the decoration link to mathematical and natural ratios
Striking synthesis of tradition and innovation. The dimensions of the interior height and the diameter of the dome are the same (43.2m). The architect, who is unknown, did this on purpose to show the harmony of the building.
The Pantheon portico or entryway is a symmetrical, classical design with three rows of Corinthian columns—eight in the front and two rows of four — topped by a triangular pediment. The granite and marble columns were imported from Egypt, a land that was part of the Roman Empire.
Decorations and other features
Hadrian wanted to show off his own personal power by stamping his name on each of the bricks that were used in the Pantheon
Most likely dedicated to the planetary gods → from statues in the niches inside. Statues once stood in the niches representing the seven planetary gods
Richly decorated Pantheon is a testament to the splendor of the Roman Empire → The Pantheon is decorated in a rich marble veneer and the dome, a reflection of heaven, had gilded rosettes to represent stars on the painted blue background.
Skillful use of repetition is important in such a symmetrical design. The coffering on the underside of the ceiling lends a harmonious repetitive pattern. The juxtaposition of the alternate square/circle pattern on the marble floor underlies the symbolic joining of the circle and square shapes in the grand design of the building. Light and dark values are surely the star of the show. The bright sunlight circle travelling across the shadows during the day adds a sense of movement to the structure.
The interior design of the Roman Pantheon is a striking synthesis of tradition and innovation. The dimensions of the interior height and the diameter of the dome are the same (43.2m)
Relieving arches …
Although the dome is made of concrete, the walls are brick and concrete. To support the weight of the upper walls and dome, brick arches were built and can still be seen on the exterior walls. They are called “relieving arches” or “discharging arches.”These arches provided strength and support when niches were carved out of the interior walls.
The structure of the Pantheon is comprised of a series of intersecting arches. The arches rest on eight piers which support eight round-headed arches which run through the drum from its inner to its outer face. The arches correspond to the eight bays on the floor level that house statues. In other words, relieving arches direct the loads to the thicker parts of the wall between the niches. They provide a structural component to the wall that helps prevent excessive creep or settlement in any one place within the wall. The dome itself is supported by a series of arches that run horizontally round. Romans had perfected the use of arches which helped sustain the weight of their magnanimous buildings.
The Romans were aware of the heavy nature of their building materials. So they used lighter materials toward the top of the dome. On the lowest level travertine, the heaviest material was used, then a mixture of travertine and tufa, then tufa and brick, then all brick was used around the drum section of the dome, and finally pumice, the lightest and most porous of materials on the ceiling of the dome. This use of lighter materials on top alleviated the immense weight of the dome.
If the dome of the rotunda were flipped upside down it would fit perfectly inside the rotunda. When approaching the Pantheon from the outside it appears rectangular in shape. But it is only the first small room (cella) that has corners. The rotunda is completely round.
