The capital city
For Ana, living in her community seems normal and self-explanatory, but when war happens, her community quickly realizes that Zagreb will be a primary target for the enemy. Ana goes from being in the city of the highest opportunity, because a city would bring her opportunity, to being in the city of the highest risk, because the enemy wants to cripple Croatia and will likely attempt to decimate Ana's city. This city has archetypal overtones, symbolically, especially since Ana's innocence makes Croatia into a kind of heaven for her.
Food rations
When the family begins to survive on government issued food rations, that symbolizes their animal life and its dependency on food for survival. What formerly seemed easy and obvious—eating food—has now become a risky business and a sad affair. Suddenly, Ana realizes that survival is more difficult during times of chaos than in times of order, and her experience of food becomes less carefree and fun than before.
Air raid drills
When the city starts practicing for air raids, that symbolizes the likeliness of air raids, literally. It also symbolizes a departure from the time of order for Ana who is suddenly beside herself. The raids are absolutely panicking, by design, because the city is training its citizens for survival. The whole city is shown through the air raid drills that paranoia is absolutely warranted, and they all begin to suffer unspeakable anxiety.
The skipped war
As if Ana herself had blocked the horror of war from her memory, the novel skips to her life after her survival of battle, teleporting the reader forward into her time in New York. The skipped war is a symbol for the unspeakable horror of war experienced from the innocent point of view of Ana. For Ana, the experience is the most critical experience of her life, surely, but the reader doesn't get to share it with her, as if to suggest that the truth is incommunicable.
Ana in New York
Before war, Ana was a bright and happy kid with a hope for her future, but in the aftermath of war, she is a refugee and has truly suffered. Instead of hoping for the future, her attention is constantly dragged backwards to the horror of war and dislocation, and in New York, she is chronically overwhelmed. Her grades slip, and so does she. She sinks into a depression, but the people around her don't understand why she is suffering.
