The Pantheon’s Dome: Five thousand tons of concrete and the sun.(Photo: Vanni / Art Resource, NY)

Visitors to Rome overwhelmed by all it has to offer—”the abundance of its pasts” in the words of the poet Rilke—can find relief with a stop at the Pantheon. Embodying the city’s pagan and Christian identities, the Pantheon is Rome in microcosm.

Built in the second century by the Emperor Hadrian as a temple to all the Roman gods, it is the only major work of Roman Imperial architecture still intact. It owes its survival to having been consecrated a Christian church (Santa Maria ad Martyres) in the seventh century, which placed it under papal protection.

The architect? Candidates range from Anonymous to Apollodorus of Damascus, designer of Trajan’s Column. Whoever he was, he created a work of soaring beauty that epitomizes the Roman revolution in architecture.

Seen from its north-facing front, the concrete-and-brick Pantheon consists of a pedimented entrance porch, a domed rotunda and a boxlike intermediate structure joining them. Their forms—triangle, hemisphere and rectangle—announce the underlying theme of pure geometry.

Inside, rising from a circle-and-square-patterned floor, the hemispherical coffered dome rests on a drum. The drum’s bottom level is ringed with tabernacles alternating with recessed spaces screened with columns, its upper one with blind windows and framed marble panels.

But it is what’s overhead that draws the gasps: the largest masonry dome ever built—142 feet in diameter and weighing five thousand tons—it is the paterfamilias of every structure like it erected since. At the top is one of the most famous features in architecture, the oculus. It focuses a circle of light into the Pantheon that, tracking the transit of the sun, passes slowly across the interior surfaces as the day progresses. This moving disc—glowing, silent, inexorable—transforms the Pantheon from bricks-and-mortar house of worship into an almost living thing.

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Eric Gibson
Wall Street Journal

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