What is the "glass castle" literally, and what does it signify to Jeannette and Rex as well as the rest of the family figuratively? Be specific.

The glass castle sounds dreamlike, mostly because that is all it is-a dream. Rex Walls uses the metaphor to make promises to his daughters that he cannot possibly keep. Unfortunately, the children see it as something real. The glass castle follows other improbable dreams like building a gold panning machine and getting rich. The Glass castle is really built on illusion, the illusion of a magical future if the girls will just hang in there with Rex's delusional and abusive parenting.