What Is the Pantheon in Rome? History, Architecture & Facts

What the Pantheon is

Structurally, the Pantheon is a cylindrical drum carrying a hemispherical concrete dome, with a rectangular Greek-style portico of granite columns attached to the front and an intermediate block linking the two. The interior height to the oculus and the diameter of the rotunda are both about 43.3 metres, which is why the proportions are so often described as approximating a sphere set inside the space. That is a helpful description of the geometry rather than a literal survey result — published measurements vary slightly.

Today it is simultaneously an ancient monument administered by the Ministry of Culture and an active Catholic basilica. That dual identity governs almost everything about visiting it: ticketed admission, but suspended tourist access during services.

Book Pantheon Tickets, Tours & Hotels

Avoid buying your ticket on site by booking ahead — compare the official Musei Italiani ticket and the three best-known third-party providers, plus hotels next to Piazza della Rotonda.

Musei Italiani is the official Pantheon ticket seller. Third-party products may be tours, hosted-entry products or bundled services — check the exact inclusions before booking.

Dating and history

• 27 BC or shortly after: Marcus Agrippa builds the first structure on the site, under Augustus.
• 80 AD: the first Pantheon burns in the great fire; Domitian rebuilds it.
• Around 110 AD: that replacement is damaged — reportedly by lightning — under Trajan.
• Trajanic–Hadrianic period: the standing building is constructed, substantially completed under Hadrian, probably in the 120s AD. Lise Hetland's brick-stamp study argues for a start under Trajan; it is an influential redating rather than an uncontested consensus.
• Seventh century: the building passes into Christian use and is dedicated as Santa Maria ad Martyres.
• Later centuries: repairs, the loss of the portico's bronze, seventeenth-century papal building campaigns, and the nineteenth-century royal burials.

Fuller account: the history of the Pantheon.

Who designed it

No architect is securely documented. Apollodorus of Damascus, Trajan's engineer, has often been proposed because of his role on other imperial projects and the chronology of the works, but the attribution is circumstantial and remains speculative. Hadrian's own architectural interests are well attested, though "Hadrian designed it himself" goes beyond the evidence. See who built the Pantheon.

The name and the dedication

The name is traditionally interpreted as "all gods", from pan and theos. What that meant in practice is less clear: Cassius Dio, writing in the early third century, offered more than one explanation, including a reference to the dome's resemblance to the heavens. The building's original cult programme — which deities were honoured, and how the niches and aediculae were used — is not securely known, so statements that it was "a temple to all the gods" housing statues of the twelve Olympians should be read as tradition rather than documented fact. Discussion in what the name Pantheon means.

The dome

The dome spans roughly 43 metres and is still the largest unreinforced concrete dome ever constructed. Several features work together:

• Graded aggregate: heavier material low down, progressively lighter aggregate — including volcanic scoria and pumice — toward the crown.
• Varying thickness: the shell is far thicker at the springing than at the crown, and the drum below is massively built with relieving arches.
• Coffers: formed as recesses during construction rather than carved out afterwards. They remove some material and organise the surface, but their exact structural contribution is still debated.
• The oculus: it removes material at the crown, where the shell would otherwise be most awkward to close, and reduces total load.

The dome is not a mystery to modern engineering. Finite-element work by Mark and Hutchinson showed that it behaves as a cracked structure: meridional cracks have long been present, and the dome functions largely through arch action carried down into the drum rather than through intact hoop tension near the base. Long-term material behaviour in Roman concrete adds to its durability. Detail in the dome explained.

The oculus

The circular opening at the crown is about 8.9 metres across and is permanently open to the sky. It is the principal source of daylight inside — though not literally the only one, since light also enters through the bronze doors. Rain falls straight through it, and the ancient marble floor is gently convex, shedding water toward drains. More in why there is a hole in the roof and what happens when it rains.

The portico and inscription

The portico has sixteen monolithic Egyptian granite columns, each a single shaft roughly 12 metres tall. They are not all from one quarry: the grey granite and the pink-red shafts come from different Egyptian quarry regions, and some shafts were replaced in the seventeenth century after damage. Published weight estimates for a single shaft run into the tens of tonnes, but the figures quoted vary, so we give no single number.

The frieze reads M·AGRIPPA·L·F·COS·TERTIUM·FECIT — "Marcus Agrippa, son of Lucius, three times consul, built this" — retained from the earlier building on the site. Whether that reflects Hadrianic modesty, dynastic politics or ordinary Roman practice in restoring inscriptions is interpretation, not documented motive.

What's inside

• Raphael's tomb — an ancient sarcophagus beneath Lorenzetto's Madonna del Sasso, in one of the chapels on the left-hand side as you move clockwise from the entrance, with Bembo's Latin epitaph.
• Royal tombs — Vittorio Emanuele II, Umberto I and Queen Margherita, tended by the Guardia d'Onore.
• Artists and musicians — Baldassare Peruzzi, Perin del Vaga, Taddeo Zuccari, Annibale Carracci, Arcangelo Corelli.
• The floor — a marble pavement of squares and circles, gently convex and drained.
• The bronze doors — very large and very old, but their exact dating and how much of them is ancient are debated.

Room-by-room detail: what to see inside and who is buried here.

Why it survived

The single biggest factor is continuity of use: converted to a church and maintained rather than abandoned, the building was not systematically quarried for stone in the way many other ancient structures were. Its construction helped too — the graded aggregate, the thickness gradient and the great drum give it an unusually forgiving structural system.

It is not, however, the only ancient Roman building still standing or still in use: other Roman structures were also converted to churches or reused, and plenty survive in altered form. What is fair to say is that no other major ancient Roman building survives with its interior and roof so nearly intact. Two seventeenth-century bell towers, the product of papal building campaigns associated with Maderno and later with Bernini, were added above the portico and removed in the nineteenth century. Longer treatment in how the Pantheon survived. Ready to visit? See our complete Pantheon visitor guide.

Sources and further reading

• L. M. Hetland, 'Dating the Pantheon', Journal of Roman Archaeology 20 (2007) — the brick-stamp argument for a Trajanic start (one influential redating, not an uncontested consensus)
• R. Mark & P. Hutchinson, 'On the Structure of the Roman Pantheon', The Art Bulletin 68 (1986) — finite-element analysis of the dome, hoop stresses and cracking
• L. C. Lancaster, Concrete Vaulted Construction in Imperial Rome (Cambridge University Press) — aggregate grading, stepped rings and vault behaviour
• Platner & Ashby, A Topographical Dictionary of Ancient Rome — Pantheon (LacusCurtius)
• Cassius Dio, Roman History Book 69 (Hadrian) — English text, LacusCurtius
• Direzione Musei nazionali della città di Roma (Ministry of Culture) — official Pantheon page: hours, tickets and access

Facts on this page last checked: August 2026. Prices, opening hours and transport routes in Rome change — always confirm with the official source before your visit.

Continue reading about the Pantheon

Frequently Asked Questions

What does 'Pantheon' mean?

The name is traditionally interpreted from the Greek pan (all) and theos (gods). Cassius Dio already offered more than one explanation in antiquity, and the building's original dedication and cult programme remain debated. Since the seventh century it has been the Catholic basilica of Santa Maria ad Martyres.

How old is the Pantheon?

The standing building dates to the Trajanic–Hadrianic period and was substantially completed under Hadrian, probably in the 120s AD — roughly 1,900 years old. Brick-stamp research has produced an influential argument that construction began under Trajan, who died in 117.

Who built the Pantheon?

No architect is securely documented. Apollodorus of Damascus has often been proposed, but the attribution remains speculative. The building was completed under Hadrian, whose inscription credits Agrippa's earlier building on the site.

Why is the Pantheon so well preserved?

Chiefly because it was converted to Christian use and never abandoned, so it was maintained rather than quarried for material. Its construction — graded aggregate, varying dome thickness, a massive drum — also helped.

Is the Pantheon the largest dome in the world?

No. It is the largest unreinforced concrete dome ever built, at roughly 43 metres in diameter. Modern steel and reinforced-concrete domes are far larger.

Who is buried in the Pantheon?

Raphael and his fiancée Maria Bibbiena, the architect Baldassare Peruzzi, several other artists and musicians, and the royals Vittorio Emanuele II, Umberto I and Queen Margherita.