Pantheon, Rome

Lore & Background

The Pantheon was built on the site of an earlier temple commissioned by Marcus Vipsanius Agrippa during the reign of Augustus. After the original burnt down, the present building was completed by the emperor Hadrian and probably dedicated c. AD 126. Its date of construction is uncertain because Hadrian chose to re-inscribe the new temple with Agrippa's original date inscription from the older temple. The building is round in plan, except for the portico with large granite Corinthian columns (eight in the first rank and two groups of four 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. The height to the oculus and the diameter of the interior circle are the same, 43 metres (142 ft). The only surviving eyewitness descriptions of the Agrippan building's decoration come from Pliny the Elder's Natural History, who noted Syracusan bronze capitals, caryatid columns by the Athenian sculptor Diogenes, and one of Cleopatra's pearls cut in half to serve as earrings for a statue of Venus.

Reader's Guide

The Pantheon is one of the best-preserved of all Ancient Roman buildings, largely because it has been in continuous use throughout its history. Since the 7th century, it has been a church dedicated to St. Mary and the Martyrs (Latin: Sancta Maria ad Martyres), known as 'Santa Maria Rotonda.' The square in front is called Piazza della Rotonda. Its large circular domed cella with a conventional temple portico front was unique in Roman architecture, but it became a standard exemplar when classical styles were revived and has been copied many times by later architects. The name 'Pantheon' is from Ancient Greek 'Pantheion' meaning 'of, relating to, or common to all the gods,' though ancient authors never refer to Hadrian's Pantheon with the word aedes, and the Severan inscription on the architrave uses simply 'Pantheum.' The degree to which the decorative scheme should be credited to Hadrian's architects is uncertain. The Pantheon is a state property, managed by Italy's Ministry of Cultural Heritage and Activities and Tourism through the Polo Museale del Lazio.

Did You Know?

• The Pantheon's dome is still the world's largest unreinforced concrete dome, nearly two thousand years after it was built.
• The height to the oculus and the diameter of the interior circle are the same: 43 metres (142 ft).
• Hadrian chose to re-inscribe the new temple with Agrippa's original date inscription from the older temple, making the exact construction date uncertain.
• Pliny the Elder recorded that one of Cleopatra's pearls was cut in half to serve as earrings for a statue of Venus in the Pantheon.
• Since the French Revolution, the generic term 'pantheon' has been applied to other buildings where illustrious dead are honoured or buried.

Engineering a Perfect Sphere

The Pantheon's most arresting feature is its massive coffered dome, cast from Roman concrete (opus caementicium), which crowns a perfectly circular interior. The height from the floor to the central oculus—the sole opening to the sky—matches the diameter of the interior circle exactly: 43 metres, or 142 feet. This geometric harmony lends the space an almost mathematical perfection. Nearly two millennia after its completion, the dome remains the largest unreinforced concrete dome in the world. The rotunda is fronted by a conventional temple portico of large granite Corinthian columns—eight in the first rank, with two groups of four set behind—capped by a pediment. A rectangular vestibule bridges the classical porch to the circular cella behind it. This combination of a traditional Greek-style front with an entirely unprecedented round interior was unique in Roman architecture, and no earlier example of such a form is known.

Agrippa's Vision and Hadrian's Erasure

In the wake of the Battle of Actium in 31 BC, Marcus Vipsanius Agrippa launched an ambitious building programme on his own land in the Campus Martius. Between 29 and 19 BC he raised a complex of three structures aligned from south to north: the Baths of Agrippa, the Basilica of Neptune, and the Pantheon itself. Scholars suspect the Pantheon and the Neptune basilica were Agrippa's private sacred buildings (sacra privata) rather than public temples, which would explain how the structure so readily shed its original identity in the centuries that followed. The only surviving eyewitness descriptions of the Agrippan building's decoration come from Pliny the Elder's Natural History, who noted Syracusan bronze capitals, caryatid columns by the Athenian sculptor Diogenes, and even a fragment of one of Cleopatra's famous pearls set as an earring on a statue of Venus. After the original structure burned down in the fire of 80 AD, Domitian rebuilt it, but it burnt again in 110 AD. Emperor Hadrian then commissioned a complete rebuild, probably dedicated around AD 126. In a deliberate act of erasure, Hadrian re-inscribed the new temple with Agrippa's original date, leaving the true construction date uncertain to this day.

A Name That Refuses to Be Pinned Down

The word Pantheon derives from the Ancient Greek Pantheion, combining pan- ('all') with theion ('of or sacred to a god'), suggesting a temple belonging to every deity. Yet the very idea of a single building consecrated to all gods has been seriously questioned. Cassius Dio, a Roman senator writing in Greek, offered two possible explanations: either the name arose from the many divine statues arrayed within, or from the dome's visual resemblance to the vault of heaven. Adam Ziolkowski argues this very ambiguity reveals that Pantheon was likely a popular nickname rather than a formal title. Supporting this view, Godfrey and Hemsoll observe that ancient writers never apply the word aedes to Hadrian's building, and the Severan inscription on the architrave reads simply Pantheum rather than Aedes Panthei. Livy recorded a decree that temple cellae should be dedicated to single divinities, making a multi-god dedication irregular. Since the French Revolution, when Paris's Sainte-Geneviève was deconsecrated and renamed the Panthéon of Paris, the generic term pantheon has been extended to secular halls honouring the illustrious dead.

Two Thousand Years of Unbroken Life

Few Ancient Roman structures have survived in anything like the Pantheon's condition, and the key reason is unbroken use. From AD 609 onward, the building has served as a Catholic church, the Basilica of St. Mary and the Martyrs, commonly known as Santa Maria Rotonda. The square before its portico bears the same nickname: Piazza della Rotonda. Today it is a state property administered by Italy's Ministry of Cultural Heritage and Activities and Tourism through the Polo Museale del Lazio. Its architectural influence extends far beyond Rome. Although the combination of a circular domed cella with a conventional temple front was unprecedented in the Roman world, the Pantheon became the standard reference point whenever classical architectural vocabulary was revived in later centuries. Architects have copied its form repeatedly, ensuring that the proportions and spatial logic conceived in the second century continue to shape the built environment.