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Entry 73 of 240Invention

Roman Roads and Concrete

c. 120 CE/Roman Empire/Rome
Today Across the Roman world (the Appian Way; the Pantheon, Rome)Span Roman Empire · 27 BCE – 476 CE

Rome laid roughly 250,000 miles of road, 50,000 of it paved, built in layers on drained foundations and cambered to shed water — and it invented a concrete, using volcanic ash, that sets underwater and grows stronger with age. The Pantheon's unreinforced dome has stood for nineteen centuries and is still the largest of its kind. The roads existed to move legions and tax revenue, but merchants, letters, and eventually a new religion used them too. Rome's real durability was not its army; it was that it built things that outlasted the reason for building them.

◆ Worth knowingThe recipe for Roman concrete was lost for over a millennium, and modern researchers only recently worked out that lumps in the mix, long dismissed as sloppy work, let the material heal its own cracks when water gets in.
◆ The mechanismState formation & institutional founding

A durable new order — a state, an institution, a system of rule — is deliberately built and consolidated, outlasting the people who founded it.

Also: Trade-route shift · Labor displacement

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