Symbol for this novel

I believe that an appropriate symbol for this novel would be a passport. A passport represents a "key" for a person who is a citizen of one country that can then open doors and travel to another country. The novel's symbol being a passport can represent the main characters and how they are constantly traveling from one location to the other, can represent the obvious fact that they are tourists engulfing themselves in a foreign culture, and can also represent movement of people, locations, and ideas that happens frequently in the novel.