Which civilization first built engineered, standardized long distance roads: Persia, Rome, or an earlier network?

The reading that emphasizes Persian priority: the Achaemenid Royal Road was reorganized into a unified, standardized, post-station-equipped highway under Darius I in the fifth century BC, roughly two centuries before Rome's Via Appia (312 BC). On strict chronology the Persian network is the earlier engineered long-distance road, and Herodotus's own account of its courier speed was already treating it as a marvel of state engineering centuries before Rome's network existed.

The reading that emphasizes Roman primacy: most popular and encyclopedic accounts credit Rome as "the first" engineered road network in practice, because the Roman system is what set the durable standard, layered foundations, cambered drainage, systematic surveying with the groma, applied at a scale (more than 400,000 kilometres, over 80,500 stone-paved) no earlier network approached. On this reading, chronological priority is less important than which network's engineering methods actually became the template later road builders followed.