Agrippa's Building: The First Pantheon (27–25 BC)
The first Pantheon was built by Marcus Vipsanius Agrippa, Augustus's son-in-law, between 27 and 25 BC, as part of a broader building programme in the Campus Martius area. The inscription on the frieze of the current building's pronaos — M·AGRIPPA·L·F·COS·TERTIUM·FECIT ("Marcus Agrippa, son of Lucius, built this during his third consulship") — refers to this original construction, not to Hadrian's building.
The form of Agrippa's Pantheon is still debated by scholars: it probably had a rectangular pronaos oriented southward (not north as today), with the entrance facing Via della Palombella. Stratigraphic investigations have identified structures beneath the current floor level consistent with a plan different from the present rotunda.
Agrippa's Pantheon was damaged by fire — presumably under Domitian (80 AD) — and restored. A second fire during Trajan's reign (around 110 AD) severely damaged the structure.
Hadrian's Pantheon (118–125 AD)
The building we see today was constructed by Emperor Hadrian between 118 and 125 AD (possibly completed around 128), replacing the earlier structure. Hadrian's decision to keep Agrippa's inscription on the frieze — rather than adding his own name, as was imperial custom — was a gesture of respect towards the Augustan monuments of the city, consistent with his general policy of restoring honour to his predecessors.
Recent research, including analysis of brick stamps, dates the construction primarily to Hadrian's reign, with possible finishing work under Antoninus Pius (138–161 AD).
The Rotunda
The rotunda is the architecturally revolutionary element. The interior diameter is 43.3 metres — exactly equal to the height from the floor to the apex of the dome. The building inscribes a perfect sphere within itself.
The walls are approximately 6 metres thick at the base and taper as they rise. Sixteen large niches open in the cylindrical wall: seven alternately rectangular and curved ones contain the aedicules for the gods; the one opposite the entrance is the main exedra.
The Dome
The Pantheon's dome is the largest unreinforced concrete dome ever built — and it still is. Its construction required sophisticated engineering:
Concrete composition: the mix is not uniform. At the base, where compressive forces are greatest, travertine and tufa aggregate is used (heavier); moving upward, the mix transitions progressively to crushed brick and, in the final calotte, to pumice — one of the lightest materials available at the time. This progressively reduces the weight of the structure in the zones where the dome is most vulnerable.
The coffers: the dome ceiling is articulated into five rows of 28 coffers (140 in total). They were not merely decorative: they further lightened the dome's mass by reducing the volume of concrete.
The oculus: at the apex of the dome opens a circular oculus of 8.9 metres in diameter, the only source of natural light inside. The oculus is open — it has never been glazed. When it rains, water enters; the floor is slightly convex at the centre and fitted with drainage holes to manage precipitation.
The beam of light entering through the oculus moves through the interior space during the day, progressively illuminating the walls and floor — an effect historians have interpreted as intentional, linked to the idea of a temple that receives the cosmos.
The Pronaos
Eight monolithic columns of grey Egyptian granite form the front row of the pronaos. Another eight columns, arranged in two rows behind, create the three corridors that precede the entrance. The columns have a shaft approximately 12 metres tall and Corinthian capitals in white marble.
The pronaos is connected to the rotunda by a transitional block that conceals the change in level and the formal difference between the two elements: one of the most sophisticated architectural junctions of antiquity.
The Roman Pantheon and Its Function
The name "Pantheon" literally means "all the gods" (from Greek pan + theos). The precise function of the building in antiquity is not entirely clear. It was certainly not a conventional temple: the rotunda did not permit the external rituals typical of Roman religious practice. Some scholars interpret the building as a space for imperial cult, others as a place dedicated to the constellation of planetary gods.
Cassius Dio, a writer of the 3rd century AD, reports that the name was chosen either for the beauty of the statues of the gods or because the dome resembled the sky.
Phocas's Donation and the Conversion to a Church (609 AD)
The most decisive moment for the Pantheon's survival came in 609 AD, when the Byzantine Emperor Phocas donated the building to Pope Boniface IV. The pontiff consecrated it as a Christian church dedicated to the Virgin Mary and all the martyrs: Santa Maria ad Martyres.
This act was decisive: ecclesiastical ownership protected the building from the demolitions and material spoliation that had destroyed or severely damaged almost all other ancient Roman buildings. The interior marbles, columns, and dome survived because the Pantheon was in active use as a place of worship.
The consecration was accompanied by a symbolic gesture: Boniface IV had the bones of numerous martyrs transferred from the Roman catacombs to the Pantheon, transforming the pagan temple into a Christian relic. The Feast of All Saints (1 November), established in connection with this dedication, remains one of the feasts of the Catholic liturgical calendar.
The Middle Ages: Between Use and Spoliation
Despite ecclesiastical protection, the Pantheon was not spared all medieval spoliation:
- 663 AD: the Emperor Constans II visited Rome and had the bronze roof tiles removed from the pronaos, sending them to Constantinople (where they were subsequently lost).
- c. 735 AD: Pope Gregory III had a replacement covering added to the pronaos.
- The bronze of the portico: the famous episode of «Quod non fecerunt barbari, fecerunt Barberini» — "What the barbarians did not do, the Barberini did" — refers to Pope Urban VIII's (Maffeo Barberini) decision in 1625–1626 to have the bronze beams of the portico removed to cast cannons for Castel Sant'Angelo and the baldachin for St Peter's designed by Bernini. The fact that this demolition was attributed to the "barbarian" Barberini reflects the outrage it provoked among contemporaries.
The Renaissance and Raphael's Burial (1520)
In the Renaissance, the Pantheon became a fundamental architectural point of reference. Brunelleschi studied the dome closely before designing the one for Santa Maria del Fiore in Florence. Michelangelo commented that the dome seemed the work "of an angel, not a man."
On 6 April 1520, Raphael Sanzio died in Rome at the age of 37. He was buried in the Pantheon — an extremely rare honour for a non-noble artist — at his express wish and in respect of Pope Leo X's will. Raphael's tomb is in the third niche to the left of the entrance. The sarcophagus bears a Latin inscription: Ille hic est Raphael timuit quo sospite vinci / rerum magna parens et moriente mori ("Here lies Raphael, by whom the great mother of all things feared to be surpassed while he lived, and to die when he died").
The Kings of Italy in the Pantheon
After Italian unification (1861), the Pantheon acquired a new role as a national pantheon. The first two kings of Italy are buried there:
- Victor Emmanuel II (died 9 January 1878): the first king of Italy; the Pantheon was chosen as his tomb by the government.
- Umberto I (assassinated at Monza on 29 July 1900): the second king of Italy was also buried in the Pantheon, along with his wife Queen Margherita of Savoy (died 1926).
The presence of the royal tombs marked the Pantheon as a symbolic site of Italian national identity, a role it maintained until the proclamation of the Republic (1946).
The Pantheon Today
The Pantheon is today simultaneously an active Catholic church (Santa Maria ad Martyres) and a national monument. Sunday Mass is celebrated regularly.
Since July 2023, for the first time in history, admission to the Pantheon is charged (€5 per person). Previously, entry was free. The measure generated controversy, but the funds raised are earmarked for the monument's maintenance.
The Pantheon remains one of the most visited buildings in the world, attracting over 6 million visitors per year. It is open every day, with varying hours: generally 9:00–19:00 (Monday–Saturday) and 9:00–18:00 (Sunday). Closed 1 January and 25 December.
Visit the Pantheon with a Private Driver
The Pantheon is in the heart of Rome's historic centre, one of the most heavily traffic-restricted zones. Reaching the monument by private car is complicated; parking nearby is virtually impossible.
Visit the Pantheon with a private driver: arrive directly at the entrance, with no parking or traffic stress. Service from €49. → Book your driver at myromedriver.com
Frequently Asked Questions
When did the Pantheon start charging admission? In July 2023. The full-price ticket costs €5 (reductions for Roman residents, young people, and specific categories). Previously, entry was free.
Where is Raphael's tomb? In the third niche to the left of the main entrance, dedicated to the Madonna del Sasso. The marble sarcophagus was donated by Cardinal Bibbiena and the inscription was written by Pietro Bembo.
Is the Pantheon still an active church? Yes. Sunday Mass is celebrated regularly. The Pantheon is dedicated to Santa Maria ad Martyres and maintains its function as a Catholic place of worship alongside its role as a tourist monument.
What is the hole in the Pantheon's ceiling called? It is called the oculus (Latin for "eye"). It has a diameter of 8.9 metres. It is open — it has never been glazed. When it rains, water enters and drains through openings in the floor.
Why has the Pantheon's dome never collapsed? The dome holds because of the progressively lighter concrete composition, the coffers that reduce the mass, and the compressive arch generated by the circular geometry that distributes forces downward along the walls. There are no metal ties: all stability depends on geometry and the quality of Roman concrete.
Article no. 61 — TIER S — MON-04 Pantheon Type: HISTORY Words: ~2,400