The room were the narrator reads by the fire symbolizes his safe place, were he ponders about his deceased loved one . "I ponder,weak and weary"(Poe stanza 1).
The raven represents death and how Lenore will never come back to the narrator. "On the morrow he will leave me"(stanza 10).
The darkness when he looks outside symbolizes how he feels on the inside, afraid an alone. Looking out into the dark he calls out to his beloved Lenore, who is now in darkness. "Darkness there and nothing more"( Poe stanza 4).