The Scarlet Letter contains several categories of symbolism. One category is the characters themselves. Another is nature. "Structures" is a fairly good title for another category.
Consider the following prominent structures in the novel:
- the scaffold
- the prison door
- the Governor's mansion
A few keys into the symbolic meaning of these three prominent structures in the novel are in their location, their appearance (especially when compared to things around them), and their function.
All of the structures are symbolic in the sense that they give insight into one of the themes of the book. The scaffold and the prison door are most closely related to Puritanical punishment. The governor's mansion is a symbol of the hypocrisy present in the Puritan law vs. those who carry out the laws.