The Histories · 5.53

This is the number of stages with resting-places, as one goes up from Sardis to Susa: and if the royal road has been rightly measured as regards leagues, and if the league is equal to thirty furlongs, (as undoubtedly it is), the number of furlongs from Sardis to that which is called the palace of Memnon is thirteen thousand five hundred, the number of leagues being four hundred and fifty. So if one travels a hundred and fifty furlongs each day, just ninety days are spent on the journey.

Herodotus of Halicarnassus · trans. G. C. Macaulay, 1890
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