One thing to consider here is your statement that the city has grown. I am assuming that you plan to populate the blank area with a lot of buildings.

Cities that grow - usually show signs of that growth, such as an inner wall, smaller market areas, that are replaced with larger ones, original buildings are usually closer together and haphazardly placed, where newer ones are kept further apart. The best part of town is always moving to a nicer location with more open space.

If the walls of the city start out small, they will usually be expanded, take sharp turns to avoid new buildings, or be completely abandoned in place when new ones are built further out.

Hope this gives you some ideas.