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Today we’re headed to the heart of where it all began, Rome, as we explore #3 – The Pantheon!
It was so well preserved in large part because it has been in continuous use throughout its history. After the Fall of the Western Roman Empire, the temple has served as a Roman Catholic Church dedicated to St. Mary and the Martyrs since the 7th Century.
Commissioned by Marcus Vipsanius Agrippa on the site of an earlier temple during the reign of Augustus (27 BC – 14 AD), the present building was completed by the Emperor Hadrian. Hadrian retained Agrippa’s original inscription, which has confused its date of construction as the original Pantheon burnt down so it is not certain when the present one was built.
The building is circular with a portico of large granite Corinthian columns (8 in the 1st rank and 2 groups of 4 behind) under a pediment. A rectangular vestibule links the porch to the rotunda, which is under a coffered concrete dome, with a central opening (oculus) to the sky.
Almost 2,000 years after it was built, the Pantheon’s dome is still the world’s largest unreinforced concrete dome. The height to the oculus and the diameter of the interior circle are the same, 142 feet.
The Pantheon’s large circular domed cella, with a conventional temple portico front, is “unique” in Roman architecture. Nevertheless, it became a standard exemplar when classical styles were revived, and has been copied many times by modern architects
The building was originally approached by a flight of steps, although later construction raised the level of the ground leading to the portico, eliminating the steps. The pediment was decorated with relief sculpture, probably of gilded bronze.
Holes marking the location of clamps that held the sculpture suggest that its design was likely an eagle within a wreath. Ribbons extended from the wreath into the corners of the pediment.
Mark Wilson Jones has attempted to explain the design adjustments carried out in relating the porch to the dome, arguing that the Pantheon’s porch was originally designed for monolithic granite columns with shafts 50 Roman feet tall (weighing about 100 tons) and capitals 10 Roman feet tall in the Corinthian style. The taller porch would have hidden the 2nd pediment visible on the intermediate block.
Instead, after the intended columns failed to arrive, the builders made many awkward adjustments in order to use shafts 40 Roman feet tall and capitals 8 Roman feet tall. This substitution was probably a result of logistical difficulties at some stage in the construction.
The grey granite columns that were actually used in the Pantheon’s pronaos were quarried in Egypt at Mons Claudianus in the eastern mountains. Each was 39 feet tall, 5 feet in diameter, and 60 tons in weight.
These were dragged more than 62 miles from the quarry to the river on wooden sledges. They were floated by barge down the Nile River when the water level was high during the spring floods, and then transferred to vessels to cross the Mediterranean Sea to the Roman port of Ostia.
There, they were transferred back onto barges and pulled up the Tiber River to Rome. After being unloaded near the Mausoleum of Augustus, the site of the Pantheon was still about 2,297 feet away, so it was still necessary to either drag them or to move them on rollers to the construction site.
The large bronze doors to the cella, once plated with gold, are ancient but not the original ones of the Pantheon. The current doors, manufactured too small for the door frames, have been there since about the 15th Century.
The 4,999 short tons weight of the Roman concrete dome is concentrated on a ring of voussoirs 30 feet in diameter that form the oculus, while the downward thrust of the dome is carried by 8 barrel vaults in the 21 feet thick drum wall into 8 piers. The thickness of the dome varies from 21 feet at the base of the dome to 3.9 feet around the oculus.
The materials used in the concrete of the dome also varies. At its thickest point, the aggregate is travertine, then terracotta tiles, then at the very top were the porous light stones tufa and pumice.
Typically, at the very top, the dome would be at its weakest and vulnerable to collapse. This is not the case, however, with the Pantheon for the oculus actually lightens the load.
No tensile test results are available on the concrete used in the Pantheon, but natural stresses in the dome were found to be substantially reduced by successively using less dense aggregate stones in higher layers of the dome. If normal weight concrete had been used throughout, the stresses in the arch would have been some 80% greater.
The top of the rotunda wall features a series of brick relieving arches, visible on the outside and built into the mass of the brickwork. The Pantheon is full of such devices, an example is the many relieving arches over the recesses inside that were hidden by marble facing on the interior and possibly by stone revetment or stucco on the exterior.
The height to the oculus and the diameter of the interior circle are the same, 142 feet, so the whole interior would fit exactly within a cube. Also, the interior could house a sphere 142 feet in diameter.
These dimensions make more sense when expressed in ancient Roman units of measurement: the dome spans 150 Roman feet; the oculus is 30 Roman feet in diameter; the doorway is 40 Roman feet high. The Pantheon still holds the record for the world’s largest unreinforced concrete dome, while also being substantially larger than earlier domes.
Though often drawn as a free-standing building, there was a building at its rear into which it abutted. While this building helped buttress the rotunda, there was no interior passage from one to the other.
The interior of the dome was possibly intended to symbolize the arched vault of the heavens. The oculus at the dome’s apex and the entry door are the only natural sources of light in the interior.
Throughout the day, light from the oculus moves around this space in a reverse sundial effect. The oculus also serves as a cooling and ventilation method and, during storms, a drainage system below the floor handles the rain that falls through the oculus.
The dome features sunken panels (coffers) in 5 rings of 28. This evenly spaced layout was difficult to achieve and, it is presumed, had symbolic meaning, either numerical, geometric, or lunar.
Circles and squares form the unifying theme of the interior design. The checkerboard floor pattern contrasts with the concentric circles of square coffers in the dome.
Each zone of the interior, from floor to ceiling, is subdivided according to a different scheme. Thus, the interior decorative zones do not line up.
The overall effect is immediate viewer orientation per the major axis of the building, even though the cylindrical space topped by a hemispherical dome is inherently ambiguous. This discordance has not always been appreciated, and the attic level was redone affording a Neoclassical taste in the 18th Century.
In the aftermath of the Battle of Actium (31 BC), Marcus Agrippa started an impressive building program. The Pantheon was a part of the complex created by him on his own property in the Campus Martius in 29–19 BC, which included 3 buildings aligned from south to north (Baths of Agrippa, Basilica of Neptune, and Pantheon).
It seems likely that the Pantheon and the Basilica of Neptune were Agrippa’s sacra privata (private sacred [matters]), not aedes publicae (public temples). This less solemn designation would help explain how the building could have so easily lost its original name and purpose.
It had long been thought that the current building was built by Agrippa, with later alterations undertaken, and this was in part because of the inscription on the front of the temple which reads:
Or in full, “M[arcus] Agrippa L[ucii] f[ilius] co[n]s[ul] tertium fecit,” meaning “Marcus Agrippa, son of Lucius, made [this building] when consul for the third time.” However, archaeological excavations have shown that the Pantheon of Agrippa had been completely destroyed except for the façade.
The form of Agrippa’s Pantheon is debated. As a result of excavations in the late 19th Century, archaeologist Rodolfo Lanciani concluded that Agrippa’s Pantheon was oriented so that it faced South, in contrast with the current layout that faces North, and that it had a shortened T-shaped plan with the entrance at the base of the “T”.
This description was widely accepted until the late 20th Century. While more recent archaeological diggings have suggested that Agrippa’s building might have had a circular form with a triangular porch, and it might have also faced North, much like the later rebuildings.
The only passages referring to the decoration of the Agrippan Pantheon written by an eyewitness are in Pliny‘s Natural History. From him we know that “the capitals, too, of the pillars, which were placed by M. Agrippa in the Pantheon, are made of Syracusan bronze”, that “the Pantheon of Agrippa has been decorated by Diogenes of Athens, and the Caryatides, by him, which form the columns of that temple, are looked upon as masterpieces of excellence: the same, too, with the statues that are placed upon the roof,” and that one of Cleopatra‘s pearls was cut in half so that each half “might serve as pendants for the ears of Venus, in the Pantheon at Rome”.
The Augustan Pantheon was destroyed along with other buildings in a huge fire in the year 80 AD. Domitian rebuilt the Pantheon, which was burnt again in 110 AD.
The degree to which the decorative scheme should be credited to Hadrian’s architects is uncertain. Finished by Hadrian but not claimed as one of his works, it used the text of the original inscription on the new façade.
The Historia Augusta says that Hadrian dedicated the Pantheon in the name of the original builder, but the current inscription could not be a copy of the original. It provides no information as to who Agrippa’s foundation was dedicated to, and it was highly unlikely that in 25 BC Agrippa would have presented himself as Consul Tertium (3rd Consulship).
Cassius Dio, a Graeco-Roman Senator, Consul and author of a comprehensive History of Rome, writing approximately 75 years after the Pantheon’s reconstruction, mistakenly attributed the domed building to Agrippa rather than Hadrian. Dio appears to be the only near-contemporaneous writer to mention the Pantheon.
Even by the year 200, Dio writes that there was uncertainty about the origin of the building and its purpose:
Agrippa finished the construction of the building called the Pantheon. It has this name, perhaps because it received among the images which decorated it the statues of many gods, including Mars and Venus; but my own opinion of the name is that, because of its vaulted roof, it resembles the heavens.
In 202, the building was repaired by the joint emperors Septimius Severus and his son Caracalla, for which there is another, smaller inscription on the architrave of the façade, under the aforementioned larger text. This now-barely legible inscription reads:
IMP · CAES · L · SEPTIMIVS · SEVERVS · PIVS · PERTINAX · ARABICVS · ADIABENICVS · PARTHICVS · MAXIMVS · PONTIF · MAX · TRIB · POTEST · X · IMP · XI · COS · III · P · P · PROCOS · ET
IMP · CAES · M · AVRELIVS · ANTONINVS · PIVS · FELIX · AVG · TRIB · POTEST · V · COS ·PROCOS · PANTHEVM · VETVSTATE · CORRVPTVM · CVM · OMNI · CVLTV · RESTITVERVNT
In English, this means:
Emp[eror] Caes[ar] L[ucius] Septimius Severus Pius Pertinax, victorious in Arabia, victor of Adiabene, the great victor in Parthia, Pontif[ex] Max[imus], 10 times tribune, 11 times emperor, 3 times Consul, P[ater] P[atriae], Proconsul, and
Emp[eror] Caes[ar] M[arcus] Aurelius Antoninus Pius Felix Aug[ustus], 5 times tribune, Consul, Proconsul, have carefully restored the Pantheon ruined by age.
In 609, the Byzantine Emperor Phocas gave the building to Pope Boniface IV, who converted it into a Christian church and consecrated it to St. Mary and the Martyrs on 13 May 609. Twenty-eight cartloads of holy relics of martyrs were said to have been removed from the catacombs and placed in a porphyry basin beneath the high altar.
The building’s consecration as a church saved it from the abandonment, destruction, and the worst of the spoliation that befell the majority of ancient Rome’s buildings during the early medieval period. Paul the Deacon records the spoliation of the building by the Emperor Constans II, who visited Rome in July 663:
Remaining at Rome twelve days he pulled down everything that in ancient times had been made of metal for the ornament of the city, to such an extent that he even stripped off the roof of the church [of the blessed Mary], which at one time was called the Pantheon, and had been founded in honour of all the gods and was now by the consent of the former rulers the place of all the martyrs; and he took away from there the bronze tiles and sent them with all the other ornaments to Constantinople.
Much fine external marble has been removed over the centuries – for example, capitals from some of the pilasters are in the British Museum. Two columns were swallowed up in the medieval buildings that abutted the Pantheon on the east and were lost.
In the early 17th Century, Urban VIII Barberini tore away the bronze ceiling of the portico and replaced the medieval campanile with the famous twin towers called “the ass’s ears” which were not removed until the late 19th Century. The only other loss has been the external sculptures, which adorned the pediment above Agrippa’s inscription, while the marble interior has largely survived with extensive restoration.
Since the Renaissance, the Pantheon was the site of some important burials. Among those buried there are: painters Raphael and Annibale Carracci; the composer Arcangelo Corelli; architect Baldassare Peruzzi; and Kings of Italy Vittorio Emanuele II and Umberto I, as well as Umberto’s Queen, Margherita. In the 15th Century, the Pantheon was adorned with paintings: the best-known is the Annunciation by Melozzo da Forlì.
Pope Urban VIII ordered the bronze ceiling of the Pantheon’s portico melted down. Most of the bronze was used to make bombards for the fortification of Castel Sant’Angelo, with the remaining amount used by the Apostolic Camera for various other works.
It is also said that the bronze was used by Bernini in creating his famous baldachin above the high altar of St. Peter’s Basilica. According to at least one expert, however, the Pope’s accounts state that about 90% of the bronze was used for the cannon, and that the bronze for the baldachin came from Venice.
In 1747, the broad frieze below the dome with its false windows was restored, but the restoration bore little resemblance to the original. In the early decades of the 20th Century, a piece of the original, as could be reconstructed from Renaissance drawings and paintings, was recreated in one of the panels.
As the best-preserved example of an Ancient Roman monumental building, the Pantheon has been enormously influential in Western architecture from at least the Renaissance on. Other versions or variations inspired by the Pantheon include: Brunelleschi‘s 138 foot dome of Santa Maria del Fiore in Florence (1436); the church of Santa Maria Assunta in Ariccia by Gian Lorenzo Bernini (1664); Belle Isle House (1774) in England, Thomas Jefferson‘s library at the University of Virginia, The Rotunda (1817–26); and the 19th Century Rotunda of Mosta in Malta.
The style of the Pantheon can be detected in many buildings of the 19th and 20th Centuries. Numerous government and public buildings, city halls, universities, and public libraries across Europe and the Americas echo its portico-and-dome structure.
The square in front of the Pantheon is called Piazza della Rotonda. The Pantheon is a state property, ruled by Italy’s Ministry of Cultural Heritage and Activities and Tourism through the Polo Museale del Lazio.
Today, the Pantheon is in use as a Catholic church. Masses are celebrated there on Sundays and holy days of obligation, and weddings are also held there from time to time. In 2013, the Pantheon it was visited by over 6 million people.
Till next time, Don’t Stop Rome-ing!
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Pantheon Live Webcam, Live streaming Video of the Pantheon