The Royal Road — Persian Highway of Empire

Two thousand five hundred kilometers from Susa to Sardis, with rest stations every twenty-five kilometers where fresh horses waited. A royal courier could cover the entire length in seven days — a journey that took ordinary travelers three months. The Royal Road was not just infrastructure. It was how an empire the size of a continent thought as one mind, moved as one body, and governed as one system. Herodotus said of the Persian postal system: Neither snow nor rain nor heat nor darkness keeps them from completing their appointed rounds. The United States Post Office borrowed this line for its motto.

These signs carry the road, the royal courier, the relay horse, and the network that connected the ancient world's greatest empire.