Circular structure refers to an artistic literary structure in which the reader reaches a sense of closure when the piece finds its way back to the beginning of the narrative, play or poem in its conclusion. Writers achieve circular structure through similar phrasing, subject matter or wording.
Often, smaller stories within a main story constitute circular structure. They begin and end within the main story, leaving readers right where they began. Poems also frequently demonstrate circular structure. "The Cove" by Dick Allen, "Evolution" by Langdon Smith and "New Heavens for Old" by Amy Lowell are all examples of circular structure.