Royal Road

The Royal Road was an ancient highway reorganized and rebuilt for trade in the 5th century BCE by the Achaemenid Empire. The road was built to facilitate rapid communication on the western part of the large empire from Susa to Sardis and was probably perfected under Darius I. 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.