The Pantheon

This grand conception for a temple was built in by Agrippa and dedicated to the patron gods of the Julio-Claudian family, Venus, Mars and the Divine Julius. It is doubtful, however, that the circular concept was his. The temple was restored twice, once by Domitian in 80 AD, and then by Hadrian. Archaeologists working on the foundations of the building have shown that the temple originally faced south and so the pillared porch facing north that now graces the front of the Pantheon was a later addition. The dedication on the architrave above the porch reads "M.Agrippa L.f.cos tertium fecit" ("Marcus Agrippa Luci three time consul built [it]").

No doubt the poet Shelley was writing in the romantic vein when he described the Pantheon as `the visible image of the universe', for from the outside, at least, the building is not especially beautiful (unless, of course, it was precisely that which Shelley had in mind!). Hadrian, the adopted son and successor of Emperor Trajan, became Rome's ruler. Hadrian was elegance personified. He was tall and strong, had his hair curled and his full beard groomed daily. Moreover, Hadrian saw himself as a divinely inspired poet, with an avid interest in Hellenic culture, especially literature, music and architecture - so much so that his contemporaries snidely called him "the Greekling." The Emperor Hadrian who probably designed it personally was not really a brilliant architect, and it had always been something of a problem for the Romans to bring together the idea of a professional frontage (which they were inclined to walk through, as in their triumphal arches) with a rotunda, which has by definition no clear axis.

The Roman frontage in the `Greek manner', with its eight Corinthian columns, is pleasing enough, and no doubt it was even beautiful when the bronze statues were still in place on the pediment. The exterior of the rotunda is also quite pleasant, and here again, in former days, when still covered with its marble and stucco facing, it might have been extremely beautiful. But, the two together - the rectilinear frontage and the curvilinear rotunda - form something of an absurdity, and I find it almost impossible to stand in Piazza della Rotunda, and look towards this famous building without smiling to myself. Yet, even as I give this personal opinion, I must in fairness record that others do not always agree with me. In his fine book on Rome, Stewart Perowne records that the Pantheon is `one of the most beautiful, most important buildings in the world'.

Once past the portico, and inside the building, the unlikely union of straight lines and curves is forgotten, and one stands amazed at the space within, which reveals what Shelley had in mind, for the universe itself is expressed as articulated space. Not only was this interior, constructed between An 119 and 128, the largest enclosed space in the ancient world, but it was also one of the most beautiful and perfect in design. The structure is much the same as when it was built, in spite of frequent restorations.

The rotunda is a perfect circle, with an inner diameter of 142 feet; the vertical walls are 20 feet thick, with indented recesses 14 feet deep, each fronted with columns. The rotunda was originally covered with gilded bronze plates, which were moved by Constans II in AD 663 and taken to the `New Rome' of Constantinople. The portico is 110 feet wide, and 60 feet deep in the centre.

Hadrian's engineers began clearing the site and preparing the foundations. They dug a circular trench 26 feet wide and 15 feet deep for the rotunda's foundation and rectangular trenches for the pronaos and the connector. They lined the trenches with timber forms and layered those with pozzolana cement - a powerful cement that the Romans discovered they could make by grinding together lime and a volcanic product found at Pozzuoli, Italy. Though the Romans had been building with concrete since about 200 BC, work on the Pantheon was difficult and proceeded in gradual stages. Other buildings surrounded the site so laborers lacked space in which to work.

Vitruvius (cir. 20 BC), a noted Roman architect, recorded the process followed in his day, that was probably still used by the Pantheon's builders. The ancients hand mixed wet lime and volcanic ash in a mortar box, adding very little water so that they got a nearly dry composition. They carried this mixture to the job site in baskets and poured it over a prepared layer of rock pieces. They then tamped the mortar into the rock layer. The tamping packed the mortar, reduced the need for excess water, but, at the same time, stimulated bonding.

Transportation presented another problem. Just about everything had to come down the Tiber by boat, including the 16 gray granite columns Hadrian ordered for the Pantheon's pronaos. Each was 39 feet) tall, five feet in diameter, and 60 tons in weight. Hadrian had these columns quarried at Mons Claudianus in Egypt's eastern mountains, dragged on wooden sledges to the Nile, floated by barge to Alexandria, and put on vessels for a trip across the Mediterranean to the Roman port of Ostia. From there the columns were barged up the Tiber.

The Panthéon, Paris, France. King Louis XV vowed in 1744 that if he recovered from an illness he would replace the ruined church of Sainte-Geneviève (see entry Genevieve) with an edifice worthy of the patron saint of Paris. The Marquis of Marigny was entrusted with the work. He had sponsored the architect Soufflot, whom he chose for the construction of the new Église Sainte-Geneviève (today the "Panthéon"), a major work in the neoclassical style. The overall design was that of a Greek cross with massive portico of Corinthian columns. Its ambitious lines called for a vast building 110 meters long by 84 meters wide, and 83 meters high. No less vast was its crypt. The foundations were laid in 1758, but due to financial difficulties, it was only completed after Soufflot's death, by his pupil Jean-Baptiste Rondelet, in 1789. As it was completed at the start of the French Revolution, the new Revolutionary government ordered it to be changed from a church to a mausoleum for the interment of great Frenchmen, with a pediment of The Fatherland crowning the heroic and civic virtues by Jean Guillaume Moitte (replaced on the Bourbon Restoration with one by David d'Angers). Twice since then it has reverted to being a church, only to become again a temple to the great intellectuals of France. In 1851, physicist Léon Foucault demonstrated the rotation of the Earth by his experiment conducted in the Panthéon, by constructing a 67 meter Foucault pendulum beneath the central dome. The original iron sphere from the pendulum was returned to the Panthéon in 1946 from the Conservatoire National des Arts et Métiers. From 1906 to 1922 this was the site of the famous sculpture The Thinker. In 2006, Ernesto Neto, a Brazilian artist, installed "Léviathan Thot", an anthropomorphic installation inspired by the biblical monster. The art installation was in the Pantheon from September 15, 2006, until October 31 for Paris' Autumn Festival. In late 2006, a "cultural guerilla movement" calling itself Untergunther completed a year-long project where they covertly repaired the Panthéon's antique clockworks.

Eventually, work began on the concrete dome, constructed in tapering courses or steps that are thickest at the base and thinnest at the oculus. The Romans used the heaviest aggregate, mostly basalt, at the bottom and lighter materials, such as pumice, at the top. They embedded empty clay jugs into the dome's upper courses to further lighten the structure and facilitate the concrete's curing. In the dome's construction, the Romans probably used temporary wooden centering on which they layered concentric rings of masonry and concrete.

Through the ages, engineers have theorized about the centering. Some say the Romans used heavy wooden scaffolding, throughout the construction process, that reached from the floor to the oculus. Others believe that centering was not required for the lower third of the dome, so the Romans used a lighter centering system supported from the dome's interior, second cornice line. To create the dome's oculus, which acts as a compression ring, the Romans built two circles of bipedales, handmade bricks that were 23.4 inches square and 1.56 inches thick. They laid the bipedales edgewise in three vertical courses, then circled the oculus with a bronze cornice.

The statues and decorations are gone, of course, and these must certainly have improved the feeling within. The walls were constructed to allow for eight recesses, in which stood the statues of the seven planetary gods: Apollo the Sun god, Selene as goddess of the Moon, and Mercury, Venus, Mars, Jupiter and Saturn. The eighth recess framed the onlooker, the human being who was himself by way of being an image of the gods - symbolically deified in the recess which led out into the world beyond.

The Pantheon was dedicated to all the gods, and so not surprisingly it was closed in the fourth century by the first Christian Emperors. When Rome fell, the Pantheon was saved by the Byzantine Emperor Phocas donating the building to Pope Boniface IV who converted the temple into a church, Saint Mary and the Martyrs. It was rededicated to Santa Maria ad Martyres in reference to the fact that many of the bones of the early Christians (those who had turned their backs on `all the gods') were transferred there from the catacombs.

The building underwent a cosmetic change during the baroque period when Bernini was asked to add belltowers to the Pantheon. These belfries were quickly dubbed "Bernini's ass's ears" and were finally removed when the building was restored in 1883.

The light streaming down from an 27-foot opening in the crown of the rotunda, from a height which is exactly the same as the diameter of the building, as the Roman theory of architectural proportion required, is quite remarkable. We are left with a feeling of technical perfection, even a certain coldness (which is the effect which perfection in art seems to have on human beings). One feels also, perhaps, that the pagan planetary gods to whom this place was originally dedicated have not yet been completely exorcized, in spite of a thousand years of Christian ritual within the building.

Art lovers may excuse this coldness when they learn that the great Raphael is buried in this ancient space, symbolically enclosed in an antique sarcophagus, lying near to the tomb of the woman he loved. Buried here also are Victor Emmanuel II (first king of Unified Italy) and King Umberto I.

Charles Walker. Wonders of the Ancient World. Crescent Books, New York. 1980.

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