The route enters the London Borough of Islington at Goswell Road becoming a single carriageway running north from the border of the City to Angel through a mix of offices and urban housing. Goswell Road and St John Street were the ancient routes from the City to Islington, with St John Street being the start of the Great North Road until the General Post Office headquarters was built at St Martin's-le-Grand in 1829, whereafter stagecoaches used Aldersgate Street and Goswell Road. The New River originally flowed down the centre of Goswell Road, but is now underground and no trace of it can be seen at the surface. The street was reported in 1720 to be "meanly built and inhabited", containing numerous inns and brothels, and it largely remained a slum area until the rebuilding that took place after the Second World War, and in particular the residential development that spread out from the Barbican since 1980.