In To Kill a Mockingbird Harper Lee establishes the Radley house as horrific with gothic imagery from a child’s imagination.
The Radley house is the home of Nathan and Arthur Radley. Arthur never left the house and had a sordid past, giving him the nickname Boo Radley. He is “Boo” both because he is a ghost, never coming out, and because he is frightening.
The Radley Place was inhabited by an unknown entity the mere description of whom was enough to make us behave for days on end… (ch 1)
The Gothic imagery surrounding the Radley house contributes to an effect of both horror and sadness. The house is described as having drooping, “rain-rotted shingles,” and trees that “kept the sun away” with a picket fence that “drunkenly guarded” the house (ch 1).
Even though the tree drops pecans in the schoolyard, the children don’t eat them because they think they’re poisoned. The children dare each other to touch the door. All of this contributes to the spookiness of the house.