Rabbi Yehoshua Ben Levi is one of the most quoted scholars in the Talmud - assuming he was one scholar and not two, which he may have been. Whether one or two, he or they lived a very long time ago, in the 3rd century give or take a generation. (And either he, or they, or someone else of the same name, seems to be buried until this very day in Mitch Pilcer's back yard in Zippori).
In any case. Back in the 3rd century Jerusalem was a small town, roughly the size of today's Old City, which is one square kilometer. Yet the Talmud on page 50a of the Pessachim tractate cites Rabbi Yehoshua ben Levi as foretelling that in the future the city will be so large that a galloping horse will need half a day, from dawn until noon, to get from the edge of town to its center, and this in all directions.
I'm not an expert in galloping horses, but assuming one can gallop without stopping for all those hours, I expect the Jerusalem of 2013 hasn't yet reached the dimensions Yehoshua ben Lvi had in mind. Give us another 10-20 years and we'll get there, only 1,800 after he said we would.
(The Daf Yomi series, I remind you, is presented and explained here).