Mosman is a suburb on the Lower North Shore region of Sydney, in the state of New South Wales, Australia. Mosman is located 8 kilometres north-east of the Sydney central business district and is the administrative centre for the local government area of the Municipality of Mosman.

The Middle Head Fortifications is a heritage-listed former defence establishment and military fortifications and now public space located at Middle Head Road, Middle Head, Mosman in the Mosman Council local government area of New South Wales, Australia. It is also known as the Middle Head Military Fortifications or The Old Fort. The fortifications consist of the Outer Middle Head Battery located at the end of Old Fort Road, the Inner Middle Head Battery located at the end of Governors Road, and the Obelisk batteries reached by a path from the corner of Middle Head Road and Chowder Bay Road. The fortifications at Middle Head formed part of Sydney Harbour's defences. The property is owned by the Department of Planning and Environment. It was added to the New South Wales State Heritage Register on 2 April 1999.