I love this picture because it gives a better sense than any other I’ve seen of the sheer size of this structure, built in the 2nd century AD. Cracks like this one are still visible if you look closely at the dome; they have been covered up by a mortar or cement slightly lighter than the rest of the surface. This covering is simply cosmetic rather than structural, as this engineer explains:
“Too often, we’re trying to make old structures conform to theories we learned for steel and concrete,” he says. Those materials remain strong under immense stresses in modern buildings. But buildings like the Pantheon “stand because of their geometry,” he says, “and the way builders conceived them was really through their geometry.” Cracks and deformations, he argues, are not necessarily flaws; they’re often a sign that a building adapted to a sinking foundation centuries ago and found a new conformation.
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