3.Glass Castle- How does the title relate to the book?

The title Glass Castle relates to the book because that is the house that her father promised when he would get enough money that he would build for his family. Throughout her childhood he would continue to promise her that one day he would build it. I also believe that it symbolizes that one promise that he promises her and how he never kept that promise and how she always longed for it. It is the one thing that always stayed the same. Even though many things in their life were not this promise remained the same.