Royal Road

The Royal Road was an ancient highway reorganized and rebuilt by the Persian king Darius the Great (Darius I) of the first (Achaemenid) Persian Empire in the 5th century BCE.[1] Darius built the road to facilitate rapid communication throughout his large empire from Susa to Sardis.[2] Mounted couriers of the Angarium were supposed to travel 1,677 miles (2,699 km) from Susa to Sardis in nine days; the journey took ninety days on foot.[3]

The map of Achaemenid Empire and the section of the Royal Road noted by Herodotus