Hidden Details Most Visitors Miss in the Pantheon

1. The inscription that names the wrong builder

The Latin inscription M·AGRIPPA·L·F·COS·TERTIUM·FECIT credits Marcus Agrippa, who built the first Pantheon on this site in the 20s BC. That building was destroyed by fire, and the rotunda standing today belongs to the Trajanic–Hadrianic rebuilding of the early second century AD. The inscription was reinstated on the new building rather than replaced. Read who actually built the Pantheon.

2. The second inscription

Below Agrippa's large letters is a much smaller second line in finer carving recording an early third-century restoration under Emperors Septimius Severus and Caracalla. It is easy to miss from the middle of the piazza; stand close to the portico and look under the main inscription.

3. The mismatched portico columns

The portico's monolithic granite shafts came from Egyptian quarries in the eastern desert. Not all of them are original: three shafts on the eastern side were replaced in the seventeenth century across two papal campaigns — under Urban VIII and then Alexander VII — using granite salvaged from other ancient Roman structures. Their colour and grain differ noticeably from the originals once you look for it.

4. The pivot-hinge doors

The great bronze doors turn on pivots set into the lintel and threshold rather than side hinges, carrying their weight vertically. Whether the leaves themselves are ancient is debated — they are usually described as ancient in origin but heavily restored, with modern support fitted to relieve the pivots. Look down at the marble at the foot of each leaf for the pivot socket.

5. The missing bronze ceiling

The portico ceiling is a later replacement. The bronze that covered the portico roof structure was removed in 1625 under Pope Urban VIII (Barberini). Contemporary accounts say most of it went to the foundry at Castel Sant'Angelo; the popular claim that it became Bernini's baldachin in St Peter's is contested by historians. Hence the Roman jibe quod non fecerunt barbari, fecerunt Barberini.

6. The floor drains

Walk toward the centre of the rotunda and look down. Set into the marble pattern is a ring of small circular drain holes directly beneath the oculus, part of the ancient drainage design and still in use. The floor is slightly convex, so water runs toward them rather than pooling. In heavy rain the centre can be genuinely wet, and staff sometimes rope it off.

7. The missing coffer decoration

The dome carries 140 coffers in five rings. Traces of fixings suggest each once held applied decoration — usually reconstructed as gilded bronze rosettes — which is why the dome is often described as having originally glittered. The rosettes themselves do not survive, so the appearance is a reconstruction hypothesis, not a documented fact. What you see today is the bare concrete geometry.

8. The hidden relieving arches

The rotunda wall is roughly six metres thick and hollowed out with niches and internal chambers. Built into it is a network of brick relieving arches that channel load away from the openings and into the solid piers between them. You cannot see them from inside; walk around the rear exterior, where the brickwork is exposed, and the arch pattern shows through the masonry.

9. The step you walk down

You step down into the Pantheon from the piazza. In antiquity the portico was approached by steps going up from a paved forecourt. The ground level around the building has risen over two thousand years as debris, flood silt and rebuilding accumulated — the excavated ancient level sits well below today's pavement. The Pantheon has not sunk; the city grew up around it.

10. The other artist tombs

Most visitors find Raphael. Far fewer notice the memorials to Annibale Carracci, Baldassare Peruzzi, Taddeo Zuccari and others buried in the same rotunda, who followed Raphael's example. See the tombs inside the Pantheon explained.

11. The early medieval icon

Above the high altar hangs a dark icon of the Madonna and Child. Tradition connects it with the building's consecration as a Christian church in the early seventh century; art historians date the surviving panel later and note substantial repainting. Either way it is one of the oldest objects on display in the building.

12. The royal honour guards

The men standing quietly by the royal tombs are not security staff. They are volunteers of the Istituto Nazionale per la Guardia d'Onore alle Reali Tombe del Pantheon, an association that has kept a voluntary vigil at the tombs of Italy's first two kings since the late nineteenth century.

13. The April 21 sunbeam

Around 21 April, Rome's traditional founding date, the midday beam from the oculus falls across the entrance wall and the grille above the doorway. Several scholars read this as a deliberate Hadrianic alignment; others treat it as a by-product of the geometry, since similar effects occur on neighbouring dates. Treat it as a plausible but unproven intention. More in the Pantheon oculus explained.

Photography inside is allowed for personal use, but not during Mass — if a service is in progress, put the phone away and wait.

Sources and further reading

• Encyclopaedia Britannica — Pantheon, Rome: structure, dating and history
• Direzione Musei nazionali della città di Roma (Ministry of Culture) — official Pantheon page: hours, tickets and access
• Istituto Nazionale Guardia d'Onore alle Reali Tombe del Pantheon — official site
• Sovrintendenza Capitolina ai Beni Culturali — Rome's monuments and conservation
• Italian Ministry of Culture — Pantheon institutional page
• UNESCO World Heritage List — Historic Centre of Rome

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's the most overlooked detail in the Pantheon?

The small drainage holes set into the marble floor beneath the oculus. They belong to the ancient drainage design and still carry rainwater away without modern pumping.

Why are the portico columns different colours?

Not all of them are original. Three columns on the eastern side of the portico were lost over the centuries and replaced in the seventeenth century with granite shafts of a different colour taken from other ancient buildings in Rome.

Is there a second inscription on the Pantheon?

Yes. Beneath Agrippa's large dedication is a smaller line in finer letters recording an early third-century restoration under Septimius Severus and Caracalla. Most visitors never notice it.

Can you see the relieving arches from inside?

No. They sit inside the thickness of the rotunda wall. Traces of the pattern are visible in the exposed brickwork on the outside of the building at the rear.

What happens to rain that falls through the oculus?

It runs across the slightly convex marble floor into the ancient drain holes and is carried away by a drainage system beneath the building. In heavy rain the floor can be wet and staff may cordon off the centre.