Which empire built the ancient road network known as the Royal Road?

The Achaemenid Empire built the ancient road network known as the Royal Road.

The Royal Road was improved and organised under the Achaemenid Persian ruler Darius I, who reigned from 522 to 486 BC. Its best-known route connected Susa in southwestern Iran with Sardis in western Anatolia, a distance of roughly 2,700 kilometres.

The road supported rapid communication, administration, trade, and military movement across the empire. Royal messengers used relay stations, where fresh horses were available. Herodotus praised the system in his account of Persian communications, noting that couriers could cover the route far faster than ordinary travellers.

The Royal Road was not necessarily one continuous paved highway in the modern sense. It incorporated established routes and crossings, and its exact alignment changed over time. The later Roman road system is more familiar to many readers, but the Royal Road belonged to the earlier Achaemenid Persian state.