Roman Roads and Concrete

c. 120 CE — Roman Empire, Rome

Today: Across the Roman world (the Appian Way; the Pantheon, Rome)

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 knowing: The 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.

Pattern: State 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.

Entry 73 of 240 in Precedent, a walk through the whole human story in order.