Different measures were introduced to help solve the problem of maintaining such a massive empire. One of the more important solutions was the construction of the royal highway. The highway ran 2,700 km (1678 miles) from Susa, in Persia, to Sardis, in Anatolia. Along the highway, at 24 km (15 mile) intervals, walled inns were constructed so that dignitaries and ordinary travelers alike could rest safely. Other highways served different parts of the empire, together making up an imperial highway system. This played an important role in facilitating trade, communication, and troop movement. During times of war, storehouses were also set up to support advancing troops. The royal highway was extremely efficient, and Herodotus considered it "excellent".

Another measure was the introduction of a postal service that would operate throughout the empire. Riders were trained and horses specially bred for the purpose of endurance and speed. Riders would carry their mail for a day, and the mail would be carried the next day by a fresh horse and rider. It took only seven days to get a letter from Susa to Sardis, when previously it had taken three months. Interestingly, this Achaemenid innovation, by way of the Greeks and Romans, heavily influenced the postal system of Europe. It also survived in Iran up until the local introduction of the telegraph.

Shadows in the Desert, Ancient Persia at War, Dr. Kaveh Farrokh