First we learned how the Jerusalem started as a city and moved into prominence. In Tanakh, we learned how Jerusalem was a bit of a backwater until David came establish his throne here. As is, it was never a particularly large city. Remember, in those days cities were not terribly big. It did grow of course. Now think about cities back in the ancient times. A) They were walled to protect against invaders. Jerusalem did have a huge advantage to start with being on the top of a hill. So in order to grow, you had to build a new section of wall to accommodate the increasing population. That happened in two phases. First you had the original city, then it was expanded westward and then northward. The city essentially quadrupled in size. Remember, this incorporates an area not much larger than what is termed the Old City today. Modern Jerusalem is massively larger than the area the old walls contained.
We learned why certain things are they way they are and the choices that were made when the model was built. Of course, much of what we know comes from Josephus, the great Roman historian. There are other sources of course; coins, the Christian Bible, post-Temple Jewish literature. I invite you to look at pictures at the link. Israel Museum Pics You can see certain things such as the towers. Only one is not sheer guesswork. The one in the middle is described by Josephus, the others who knows. We only know there are three towers. Such is the life of historians. I must admit to feeling sorry to another group that was being given a tour. They are getting a much less accurate description of the model without the background we received and understanding of the limitations that the model maker had.
I must admit, that was just about near the top of any museum visit I have had. You rarely the opportunity to take a tour by an expert and it was just one opportunity I refused to miss out on.