Pantheon Architecture Explained for First-Time Visitors

The piazza and approach

You arrive in Piazza della Rotonda. In the middle stands a fountain by Giacomo Della Porta (1575), topped with a small Egyptian obelisk added under Pope Clement XI in 1711. Note the ground level: the Pantheon now sits in a slight depression because the surrounding city has risen around it. In antiquity the portico was approached up steps; today you walk down towards it.

The portico

The columned porch is the Pantheon's Greek face: sixteen monolithic columns supporting a pediment, with a flat-roofed entrance hall behind. Look up at the porch ceiling — the present structure is post-antique. The ancient roof structure included bronze trusses, which were removed under Pope Urban VIII in 1625–26. Much of that metal is documented as going to cannon production for Castel Sant'Angelo; the popular claim that it became Bernini's baldachin in St Peter's is disputed.

The inscription reads M·AGRIPPA·L·F·COS·TERTIUM·FECIT — "Marcus Agrippa, son of Lucius, three times consul, built this." It refers to the earlier building on the site, not the one you are about to enter. See who built the Pantheon.

The granite columns

Each shaft is a single piece of Egyptian granite, roughly 12 metres tall and weighing on the order of dozens of tonnes — figures around 60 tonnes are commonly cited estimates. They are not all from one quarry: the grey granite shafts are associated with Mons Claudianus in Egypt's eastern desert, while the pink-red granite comes from a different Egyptian source generally associated with Aswan. Several columns on the eastern side were replaced in the seventeenth century after damage and collapse, so the portico you see mixes ancient and replacement shafts rather than sixteen identical originals.

The bronze doors

The bronze doors are about 7 metres tall and are widely considered ancient, though their exact date has been debated and they have been repaired over the centuries. They operate using an ancient pivot system — turning on pins set into the threshold and lintel rather than side hinges — which carries their weight vertically. Pause before walking through: few surviving doorways anywhere are on this scale or this old.

The rotunda

The main space is a cylinder topped by a hemisphere, with the interior diameter and the height to the oculus both about 43.3 metres. Project a sphere into the interior and it touches the floor and the crown of the dome. That relationship is the governing idea of the building.

The seven niches

Around the wall are seven niches alternating rectangular and semicircular. The niches probably held statues or cult images in antiquity, but their exact occupants are not securely documented — the familiar list of "seven planetary gods" is a modern hypothesis, not a surviving Roman inventory. Today they hold Christian altars and tombs:

• Raphael's tomb (1483–1520), on the left-hand side of the rotunda as you walk clockwise from the doors, with a Madonna by Lorenzetto above it.
• Vittorio Emanuele II, in the chapel to the right of the apse.
• Umberto I and Queen Margherita, in the chapel to the left of the apse.
• Chapels and altars with Renaissance and Baroque paintings in the remaining niches.

Full detail in who is buried in the Pantheon.

The marble floor

Large portions of the floor preserve the ancient pavement pattern and materials — yellow Numidian marble, red porphyry, grey granite — with extensive later repairs and a major nineteenth-century restoration. The pattern alternates squares and circles set within larger squares. It is gently convex and pierced by small drainage holes that carry rainwater from the oculus away; the precise convexity and drain count quoted online come from architectural surveys and should be cited to one before being repeated as exact.

The dome and coffers

Look up. The 140 coffers in five concentric rings are not decoration alone: they remove weight while preserving the shell's structural depth, and their diminishing size exaggerates the apparent height. They may originally have carried decorative rosettes and richer surface treatment, but no such decoration survives and reconstructions differ.

The oculus

The roughly 9-metre opening at the top is the oculus. It is the principal source of daylight, it removes concrete at the crown, and its thickened rim helps distribute forces around the opening — but the dome stands because of the whole system, not the hole alone. Read why there is a hole in the Pantheon's roof.

That is the building, front to back. Knowing which parts are ancient, which are replacements, and which are educated reconstruction is what turns a twenty-minute stop into a proper visit.

Sources and further reading

• Direzione Musei nazionali della città di Roma (Ministry of Culture) — official Pantheon page: hours, tickets and access
• Encyclopaedia Britannica — Pantheon, Rome: structure, dating and history
• UNESCO World Heritage List — Historic Centre of Rome
• Turismo Roma — official city tourism information

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 architectural style is the Pantheon?

Roman Imperial architecture. It combines a Greek-style columned portico with a Roman circular domed rotunda — a hybrid that became a template for Western public architecture.

What are the parts of the Pantheon called?

From front to back: the pediment, the portico, the intermediate block, the rotunda, and the dome with its oculus.

Why are the columns granite?

Egyptian granite was among the most prestigious stones in the empire and each shaft is a single monolith, so the portico is a deliberate display of imperial reach. The grey shafts are associated with the Mons Claudianus quarries; the pink-red granite is generally associated with the Aswan region.

What are the squares on the dome called?

Coffers — recessed panels arranged in five diminishing concentric rings that reduce weight while keeping structural depth. They may originally have carried rosettes and richer surface treatment, but the details of that decoration are reconstruction rather than documented fact.

How do I know what I'm looking at inside?

Stand in the middle and look up first, then walk the perimeter clockwise. Raphael's tomb is on the left-hand side of the rotunda as you walk in that direction; Vittorio Emanuele II is in the chapel to the right of the apse, Umberto I and Margherita to the left of the apse.