Who built the Pantheon in Rome?

The name on the front

Stand in the Piazza della Rotonda and look up at the porch. The big letters read:

M·AGRIPPA·L·F·COS·TERTIVM·FECIT

In full, Marcus Agrippa Lucii filius consul tertium fecit: “Marcus Agrippa, son of Lucius, consul for the third time, made this.” Agrippa’s third consulship was 27 BC, the year his friend Octavian became Augustus. Below it, in smaller letters, a second inscription records a restoration by the emperors Septimius Severus and Caracalla in AD 202. Neither text names the man who built what you are looking at.

Agrippa’s Pantheon

Marcus Vipsanius Agrippa was Augustus’s friend from their student days and the general Augustus never was. He commanded the fleet that won at Actium in 31 BC, built aqueducts, among them the Aqua Virgo that still feeds the Trevi Fountain, and in 21 BC married Augustus’s daughter Julia. He also filled the Field of Mars with baths, porticoes and temples. Cassius Dio records that he completed the Pantheon in 25 BC, and wonders about the name. Perhaps, Dio says, it held statues of many gods, Mars and Venus among them, but he preferred to think the vaulted roof looked like the heavens.

Agrippa wanted to name the building after Augustus and set up his statue inside. Augustus refused both honors. So Agrippa put a statue of the deified Julius Caesar in the temple and statues of Augustus and himself in the porch (Dio 53.27).

Hadrian’s rebuilding

Agrippa’s building burned in AD 80 and was repaired under Domitian, then burned again in 110. What stands now is a new design: a columned porch joined to a vast round hall under a concrete dome. Some scholars, reading the stamps on its bricks, think work began around 114 under Trajan; it was finished under Hadrian and probably dedicated around 126. Hadrian’s ancient biographer says he restored the Pantheon and other old buildings and dedicated them all in the names of their first builders. He put his own name on none of them except the temple of his father, Trajan.

The dome is the marvel. Its inner diameter is 43.3 meters (142 feet), and the height from the floor to the top is the same, so a perfect sphere would fit inside. It is unreinforced concrete, lighter toward the crown, and open to the sky through a round eye, the oculus. Nineteen centuries later it is still the largest unreinforced concrete dome in the world.

Why it survived

In 609 the Byzantine emperor Phocas gave the building to Pope Boniface IV, who consecrated it as a church, Saint Mary and the Martyrs. A church was looked after while pagan temples were quarried for stone, so the Pantheon kept its roof. It is still a church and a tomb: the painter Raphael lies there, and so do two kings of united Italy, Victor Emmanuel II and Umberto I.

Agrippa’s family went further than his buildings. His grandson was the emperor Caligula and his great-grandson Nero. Much of the Rome of marble that Augustus boasted of lies in ruins. The best-preserved temple of ancient Rome still carries the name of his friend.