Essex is a ceremonial and non-metropolitan county in the East region of England, and one of the home counties. It is located to the northeast of Greater London and is one of the most populous counties in England. Essex County Council is the principal local authority for much of the county, sharing functions with twelve district councils. The county town is Chelmsford. The southern Essex boroughs of Thurrock and Southend-on-Sea are governed separately as unitary authorities. It was established in antiquity and formed the eastern portion of the Kingdom of Essex. Sections of the county closer to London are part of the Metropolitan Green Belt, which prohibits development. It is the location of the regionally significant Lakeside Shopping Centre and London Stansted Airport; and the new towns of Basildon and Harlow.