Piccadilly (/ˌpɪkəˈdɪlɪ/) is a road in London, running from Hyde Park Corner in the west to Piccadilly Circus in the east. It is completely within the City of Westminster and forms part of the A4 route. The area of St. James's lies to the south of the eastern section of the street, while the western section is built up only on the northern side and overlooks Green Park.