When discussing the setting in a literary work, it is important to consider various elements that contribute to it. The location or locations, historical time period and, often, the culture surrounding the story, and the intended audience, are all important. To a Shakespearean audience and particularly to James I, the opening scene of Macbeth, with the witches, would have been culturally significant, as people were obsessed with witches and witchcraft at the time and this would have contributed to the setting as it immediately creates the mood and serves as a warning of what may follow. The castles and the battlefield, as settings, also intensify the overall atmosphere and create contrast in the play. Note the comparison between "So foul and fair a day," (I.iii.38). Note the description by Lady Macbeth regarding Duncan's arrival at Macbeth's castle, a place in which Duncan should feel safe: "The fatal entrance of Duncan under my battlements," (I.v.36). The locations constantly serve as reminders that there is far more going on than is outwardly shown; reinforcing the themes relating to power and control and appearance and reality.
There is also historical merit in Macbeth, although the story is fictional. The real Macbeth, of eleventh century Scotland did in fact kill Duncan and ascend to the throne although it is believed that Duncan was the oppressor and Macbeth was the good king. Shakespeare makes sure that his version of Macbeth suits James I, to whom Shakespeare owes his loyalties.
The setting, therefore, enhances the overall intention of the play. The places which are significant become ominous reminders and symbols of the possibilities, especially after Macbeth's killing spree. The audience leaves the play with the understanding of how deception and treachery can lead to a person's complete personal destruction.