Technically, Vanity Fair is set in a fictional place called Vanity Fair, a never-ending allegorical carnival of human vice. The events of the novel take place in a puppet show held at the fair. Within the world of this show, however, the novel unfolds in a satirical version of England around the time of Napoleon's return from exile in 1815. Given that the focus of the novel is the non-stop drama of England's upper classes, a great portion of the narrative takes place in the houses of the wealthy and powerful in London and the English countryside, although some chapters unfold in Continental Europe and a short portion takes place in India, where England had a powerful colonial presence.
The larger historical context of Napoleon's return to power in France, rampage across Northern Europe, and eventual defeat at Waterloo is vital for the reader to understand, as it sets into motion several important plot points in the novel: at the beginning, the outbreak of the war financially ruins Amelia Sedley's family, while later on in the book, the conclusion of the war after Waterloo spurs Becky and Rawdon Crawley to try their luck living on no income and pantomiming aristocracy in Paris.
