Roman architecture

Rome borrows a lot from Greece. The columns, the orders, the temple gable. But the Romans are engineers first.

Their secret is concrete. Lime, water, stone – and volcanic ash from the area around Naples, which lets the mix harden even under water. With concrete you can cast vaults, and with vaults you can cover rooms no Greek had dreamed of.

So an empire of buildings grows. Aqueducts carrying water across valleys. Amphitheatres for up to fifty thousand spectators. Baths, basilicas, triumphal arches. The round arch becomes the Roman signature – it carries, it repeats, it marches across the landscape.

And then the Pantheon. The temple in Rome is probably dedicated around 126, under the emperor Hadrian. The dome is just over 43 metres across, and at the top is a round hole – the oculus – nine metres wide, open to the sky. It is still the largest dome of unreinforced concrete in the world.

Yet over the entrance stands another name: Marcus Agrippa, who built an earlier temple on the site. Hadrian leaves the inscription in place. Modesty, or propaganda?

When Rome falls, the vault lives on. Romanesque even carries the name. And the Renaissance, Neoclassicism and every Swedish customs-house portal borrow from Rome.

Ancient Greek architecture. The columns are the same, but the Greeks build with beams and stone. The Romans build with vaults and concrete – and make the room inside as important as the façade.

Romanesque. The name comes from Rome, and so does the round arch. But Romanesque means medieval stone churches, half a millennium after the fall of the Empire.