The Piccadilly line is a deep-level London Underground line running from the north to the west of London. It has two branches, which split at Acton Town, and serves 53 stations. The line serves Heathrow Airport, and some of its stations are near tourist attractions such as Piccadilly Circus and Buckingham Palace. The District and Metropolitan lines share some sections of track with the Piccadilly line. Printed in dark blue on the Tube map, it is the sixth-busiest line on the Underground network, with nearly 218 million passenger journeys in 2019.

Piccadilly Circus is a London Underground station located directly beneath Piccadilly Circus itself, with entrances at every corner. Located in Travel-card Zone 1, the station is on the Piccadilly line between Green Park and Leicester Square stations and on the Bakerloo line between Oxford Circus and Charing Cross stations.