She equates the "small and tattered tent" to "an imperial structure." This is not true on the surface. But, the intended meaning is brought out by the literary device known as exaggeration.
Explanation:
Exaggeration is the description of something by making it look or sound more than it really is. For example, if you say that Josephine killed the mosquito with a sledge hammer, it is an exaggeration. Exaggeration is a figure of speech. It is one of the literary devices employed by good authors to make meanings clearer than they would appear otherwise.