Jonah 3:3 So Jonah arose, and went unto Nineveh, according to the word of the LORD. Now Nineveh was an exceeding great city of three days' journey.
Is this an overestimate of Nineveh? The argument goes that the Bible gave Nineveh the diameter of a three-day journey, where one day equals about 20 miles -- and so, a city 60 miles in diameter. Needless to say, archaeology finds no such city that size.
The correct answer is, that Jonah's journey was not simply straight across, but roundabout, with stops for preaching; as the NIV states, Nineveh was a city that took three days to visit. Note that this is not about Jonah visiting the bazaars or shops. This is about a cultural background issue which verifies that the NIV is more or less on the mark.
Let's look at the Hebrew word for "journey" -- mahalak. It is used only four times in the OT, twice here in Jonah 3:3-4, and here:
Neh. 2:6 And the king said unto me, (the queen also sitting by him,) For how long shall thy journey be? and when wilt thou return? So it pleased the king to send me; and I set him a time.
The only other use in the OT is Ezek. 42:4:
And before the chambers was a walk of ten cubits breadth inward, a way of one cubit; and their doors toward the north.
The reference in Nehemiah is closer to hinting at the solution, though Ezekiel's reference to a fixed passageway also gives us a clue.
The background knowledge, as reported by Stuart's commentary on Hosea-Jonah , relates to the ancient practice of hospitality, and the protocol associated with making a visit to a city -- especially a diplomatic center like Nineveh.
The picture of Jonah showing up in Nineveh and just preaching isn't a realistic one. Jonah's message reached the ears of the king of Nineveh (3:6) -- do you suppose Jonah just walked into the throne room? No, and what actually happened is clued in when we are told that Jonah "began to enter into the city a day's journey" and then began preaching.
Jonah didn't spend that first day just walking into Nineveh trying to get to the center; he spent that day on his mahalak, which constituted (as indicated by the Nehemiah parallel, and as suggested by the Ezekiel reference to a fixed pathway) a structured diplomatic mission in accordance with the rules of ancient oriental hospitality.
Day 1 wasn't for preaching -- it was for being received as an emissary, and as was customary, presenting gifts to the folks in charge. A mahalak isn't merely a walk in the park; it is an itinerary.
The city of Nineveh was a "great city" -- the word "great" here was not exclusively used in reference to size, but also in the sense of might, nobility, or pride -- which required a formal itinerary of three days: a day to arrive and make introductions; a day to do the business (preaching), and a day to bid farewells and be on one's way, in accordance with ancient oriental rules of hospitality. Rihbany [The Syrian Christ, 218-9], notes how extensive these farewells can be, as the host and guest play a sort of game to see who can "win" the battle, with the host offering imprecations begging the guest to stay for just one more meal, emphasizing the dangers of the trip, while the guest actually says, "I who have been so immersed in the sea of your hospitality beg you to permit me to depart." This can go on for an extended period, even days; see an example of this in Judges 19.