The southern part of the borough is in the Central Activities Zone including Holborn, Bloomsbury and King's Cross. The northern part of the borough includes the less densely developed areas of Hampstead, Hampstead Heath and Kentish Town. Neighbouring boroughs are the City of Westminster and the City of London to the south, Brent to the west of the originally Roman Watling Street (now the A5 Road), Barnet and Haringey to the north and Islington to the east. It covers all or part of the N1, N6, N7, N19, NW1, NW2, NW3, NW5, NW6, NW8, EC1, WC1, WC2, W1 and W9 postcode areas.