Pantheon, Rome

The Pantheon is the best-preserved great building of ancient Rome, and its interior is one of the most perfect spaces ever built. The temple first raised by Marcus Agrippa under Augustus burned down; the building that stands today was reconstructed under the emperor Hadrian and completed around AD 126. With a gesture of modesty or policy, Hadrian kept the original dedication across the frieze, "M·AGRIPPA·L·F·COS·TERTIVM·FECIT", and it is still the first thing a visitor reads.

Behind the columned porch lies the rotunda, and its geometry is the whole point: the dome spans 43.3 metres and the interior is exactly as high as it is wide, so a sphere of that size would fit inside it. After almost nineteen centuries it is still the largest dome of unreinforced concrete in the world. The Roman builders made this possible by lightening the mix as it rose, from heavy travertine aggregate at the base through brick to pumice and tufa at the crown, and by hollowing the underside into five rings of 28 coffers. At the top is the oculus, about 9 metres across and open to the sky, the only source of light. Its disc of sunlight moves across the coffers and the marble floor through the day, and when it rains the water falls straight in and drains away through holes in the slightly sloping pavement.

The porch is an event in itself: sixteen monolithic granite columns, each about 12 metres high and weighing around 60 tonnes, quarried in Egypt, grey stone from Mons Claudianus and pink from Aswan, and shipped to Rome. The great bronze doors are Roman and among the oldest in the city. Other bronze was not so lucky: in the seventeenth century Pope Urban VIII Barberini had the bronze trusses of the porch melted down, largely for cannon, prompting the Roman quip that what the barbarians had not done, the Barberini did.

The building survived because it never stopped being used. In 609 the emperor Phocas gave it to Pope Boniface IV, who consecrated it as the church of Saint Mary and the Martyrs, and it is still a church. Among the tombs in its chapels are those of the painter Raphael and the first two kings of united Italy, Victor Emmanuel II and Umberto I. Outside, Piazza della Rotonda has a fountain topped by an Egyptian obelisk.

Getting there

The Pantheon stands on Piazza della Rotonda in the historic centre of Rome, about 3 km from the city's central reference point and 2 km from Vatican City. The nearest airport is Ciampino–G. B. Pastine International Airport (CIA), about 15 km away. There is no metro station at the door; the Metro A stops at Spagna and Barberini are roughly a 10–15 minute walk away through the old streets.