Castlecrag is a suburb on the lower North Shore, 8 kilometres north of the CBD, it's a suburb of historical significance that is bounded to the north, east and south by Middle Harbour and to the west by Eastern Valley Way. Castlecrag was originally planned by the husband and wife team, Walter Burley Griffin and Marion Mahony Griffin who named the suburb after a towering crag of rock overlooking Middle Harbour, known locally as Edinburgh Castle.