High Quality Content by WIKIPEDIA articles! Cowan is a suburb of northern Sydney, in the state of New South Wales, Australia. Cowan is located 40 kilometres north of the Sydney central business district, in the local government area of Hornsby Shire and is part of the North Shore region. Cowan shares the postcode of 2081 with Berowra. Brooklyn, which lies 6 kilometres to the north-east of Cowan, is the northernmost suburb of the Greater Sydney Metropolitan Area.