Cossington is a heritage-listed residence located at 43 Ku-Ring-Gai Avenue, in the Sydney suburb of Turramurra in the Ku-ring-gai Council local government area of New South Wales, Australia. It was designed by Nixon and Allen and built in 1899. It is also known as Sylvan Fells and Sylvan Falls. The property is privately owned. It was added to the New South Wales State Heritage Register on 18 August 2006.