Pantheon

The name "Pantheon" is from the Ancient Greek "Pantheion" (Πάνθειον) meaning "of, relating to, or common to all the gods": (pan- / "παν-" meaning "all" + theion / "θεῖον"= meaning "of or sacred to a god"). The simplest explanation for the name is that the Pantheon was a temple dedicated to all the gods. However, the concept of a temple dedicated to all the gods has been questioned. Ziegler tried to collect evidence of pantheons, but his list consists of simple dedications "to all the gods" or "to the Twelve Gods", which are not necessarily true pantheons in the sense of a temple housing a cult that literally worships all the gods. The only definite pantheon recorded earlier than Agrippa's was at Antioch in Syria, though it is only mentioned by a sixth-century source. Cassius Dio, a Roman senator who wrote in Greek, speculated that the name of the Pantheon comes either from the statues of many gods placed around this building, or from the resemblance of the dome to the heavens. According to Adam Ziolkowski, this uncertainty strongly suggests that "Pantheon" (or Pantheum) was merely a nickname, not the formal name of the building.

Godfrey and Hemsoll point out that ancient authors never refer to Hadrian's Pantheon with the word aedes, as they do with other temples, and the Severan inscription carved on the architrave uses simply "Pantheum", not "Aedes Panthei" (temple of all the gods). Livy wrote that it had been decreed that temple buildings (or perhaps temple cellae) should only be dedicated to single divinities, so that it would be clear who would be offended if, for example, the building was struck by lightning, and because it was only appropriate to offer sacrifice to a specific deity (27.25.7–10). Godfrey and Hemsoll maintain that the word Pantheon "need not denote a particular group of gods, or, indeed, even all the gods, since it could well have had other meanings. ... Certainly the word pantheus or pantheos, could be applicable to individual deities. ... …

In the aftermath of the Battle of Actium (31 BC), Marcus Vipsanius 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 three buildings aligned from south to north: the Baths of Agrippa, the Basilica of Neptune, and the Pantheon. It seems likely that the Pantheon and the Basilica of Neptune were Agrippa's sacra privata, not aedes publicae (public temples). The former would help explain how the building could have so easily lost its original name and purpose (Ziolkowski contends that it was originally the Temple of Mars in Campo) in such a relatively short period of time.

The only passages referring to the decoration of the Agrippan Pantheon written by an eyewitness are in Pliny the Elder'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 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, Ziolkowski complains that their conclusions were based entirely on surmise; according to him, they did not find any new datable material, yet they attributed everything they found to the Agrippan phase, failing to account for the fact that Domitian, known for his enthusiasm for building and known to have restored the Pantheon after 80 AD, might well have been responsible for everything they found. …

The floor level of the portico originally rose seven steps (1.30 metres) above the paving of the original forecourt. Repeated flooding of the Tiber and the demise of draining systems raised the level of the ground leading to the portico, covering most of these 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.

On the intermediate block between the portico and the rotunda, the remains of a second pediment suggests that the existing portico is much shorter than originally intended. A portico aligned with the second pediment would fit columns with shafts 50 Roman feet (14.8 metres) tall and capitals 10 Roman feet tall (3 metres), whereas the existing portico has shafts 40 Roman feet (11.9 metres) tall and capitals eight Roman feet (2.4 metres) tall.

Mark Wilson Jones has attempted to explain the design adjustments by suggesting that, once the higher pediment had been constructed, the required 50-foot columns failed to arrive (possibly as a result of logistical difficulties). The builders then had to make some awkward adjustments to fit the shorter columns and pediments. Rabun Taylor has noted that, even if the taller columns were delivered, basic construction constraints may have prevented their use. Assuming that each column would first be laid on the floor next to its pediment before being pivoted upright (using something like an A-frame), there would be a space requirement of a column-length on one side of the pediment, and at least a column-length on the opposite side for the pivoting equipment and ropes. With 50-foot columns, "there was no way to sequence the erection of [the columns] without creating a hopeless snarl. …

The present high altar and the apses were commissioned by Pope Clement XI (1700–1721) and designed by Alessandro Specchi. Enshrined on the apse above the high altar is a 7th-century Byzantine icon of the Virgin and Child, given by Phocas to Pope Boniface IV on the occasion of the dedication of the Pantheon for Christian worship on 13 May 609. The choir was added in 1840, and was designed by Luigi Poletti.

The first niche to the right of the entrance holds a Madonna of the Girdle and St Nicholas of Bari (1686) painted by an unknown artist. The first chapel on the right, the Chapel of the Annunciation, has a fresco of the Annunciation attributed to Melozzo da Forlì. On the left side is a canvas by Clement Maioli of St Lawrence and St Agnes (1645–1650). On the right wall is the Incredulity of St Thomas (1633) by Pietro Paolo Bonzi.

The second niche has a 15th-century fresco of the Tuscan school, depicting the Coronation of the Virgin. In the second chapel is the tomb of King Victor Emmanuel II (died 1878). It was originally dedicated to the Holy Spirit. A competition was held to decide which architect should design it. Giuseppe Sacconi participated, but lost – he would later design the tomb of Umberto I in the opposite chapel.

Manfredo Manfredi won the competition, and started work in 1885. The tomb consists of a large bronze plaque surmounted by a Roman eagle and the arms of the house of Savoy. The golden lamp above the tomb burns in honor of Victor Emmanuel III, who died in exile in 1947.

The third niche has a sculpture by Il Lorenzone of St Anne and the Blessed Virgin. In the third chapel is a 15th-century painting of the Umbrian school, The Madonna of Mercy between St Francis and St John the Baptist. It is also known as the Madonna of the Railing, because it originally hung in the niche on the left-hand side of the portico, where it was protected by a railing. It was moved to the Chapel of the Annunciation, and then to its present position sometime after 1837. The bronze epigram commemorated Pope Clement XI's restoration of the sanctuary. On the right wall is the canvas Emperor Phocas presenting the Pantheon to Pope Boniface IV (1750) by an unknown. There are three memorial plaques in the floor, one conmmemorating a Gismonda written in the vernacular. The final niche on the right side has a statue of St. …

On 23 July 1725, the Pantheon was established as the cardinal deaconry of Santa Maria ad Martyres. On 26 May 1929, the deaconry was suppressed and its title transferred to Sant'Apollinare alle Terme Neroniane-Alessandrine.

The following cardinals held the deaconry of Santa Maria ad Martyres: