Jonah 3:3 - Coke's Commentary on the Holy Bible

Now Nineveh was an exceeding great city— The account here given of Nineveh is confirmed by the testimony of heathen authors. Strabo says, that Nineveh was much greater even than Babylon: and Diodorus Siculus affirms, that its builder, Ninus, proposed to build a city of such magnitude, that it should not only be the greatest of the cities which were then in the world; but that none of those who should be born after that time, attempting the like, should easily exceed it: and a little after he subjoins, that nobody afterwards built such a city, either as to the greatness of the compass, or the magnificence of the walls. It is here said, that it was of three days' journey; that is to say, of three days' journey in circuit. Diodorus asserts, that the whole circuit of Nineveh was four hundred and eighty furlongs, which make somewhat more than sixty miles; and sixty miles were three days' journey, twenty miles a day being the common computation for a foot-traveller in the eastern countries. See Bishop Newton, vol. 1: p. 254.