It lies directly north of the Thames. For centuries the diocese covered a vast tract and bordered the dioceses of Norwich and Lincoln to the north and west. The present diocese covers and 17 London boroughs, covering most of Greater London north of the River Thames and west of the River Lea. This area covers nearly all of the historic county of Middlesex. It includes the City of London in which lies its cathedral, St Paul's, and also encompasses Spelthorne which is in modern-day Surrey.