In addition to the symbols of hope that the springtime present--the blue sky, singing birds, and "delicious breath of rain"--there are three symbols within Mrs. Mallard's house that are significant. The door to Mrs. Mallard's bedroom, the open window, and the front door of her house each represent a part of what happens to Mrs. Mallard during this eventful "story of an hour."
First, the door to Mrs. Mallard's room represents her mind and soul's inner sanctum. She retreats to her room and closes her door, staying there so long that her sister bows outside, looks through the keyhole, and begs her to open the door. That door represents her private thought life, her ability to consider her own needs for once, separate...
from the needs of anyone else, even those who love her. This is where she is able to indulge her true feelings without concern for what others will think of her.
The open window is symbolic of the years of opportunity that spread out before her now. She spreads her arms out to welcome the years that will now belong to her absolutely.
Finally, the front door of her home represents the public world that she must live in. It is through the front door that Mr. Richards and Josephine have presumably entered, and it is through the front door that her husband enters. This is the world that places demands upon her, either with "a kind intention or a cruel intention." The fact that Brently Mallard, her husband, has "a latchkey" to this door shows his ownership of her outer life--his ability to "impose a private will" upon her. The disconnect between her inner life and the outer life imposed upon her, now completely illuminated for the first time, is the shock that stops her heart.