At the beginning of this poem, the narrator is sort of dozing, or "nearly napping," he says, in his room—perhaps a library or study of some kind (as it contains books and a bust of Athena)—and "ponder[ing]" an old book full of "forgotten lore." He is also hoping that his books might distract him from the terrible grief that he's feeling. He says, "vainly I had sought to borrow / From my books surcease of sorrow," sorrow over his dead lover whose name, he tells us, was Lenore.
In the first stanza, the action that disturbs him is a "rapping at [his] chamber door." He hears a soft tapping at an outer door of his room, a door that leads outside. He assumes it is "'some visitor,'" and he tries to reassure himself at the end of the stanza that this is the source of the odd rapping. It does seem a bit strange that a visitor would be stopping by at this time, however. The narrator has already told us it is a dreary "midnight," and we soon learn that it is also December: hardly a hospitable night and time to be out and about in the cold and darkness.