Scotland Yard, officially New Scotland Yard, is another name for the Metropolitan Police Service and is also the name of the building where it has its headquarters. The name derives from the location of the original Metropolitan Police headquarters at 4 Whitehall Place, which had a rear entrance on a street called Great Scotland Yard. The Metropolitan Police Service is the territorial police force responsible for law enforcement in Greater London, excluding the "square mile" of the City of London which is the responsibility of the City of London Police.