Australian fortifications refer to military structures built to defend against potential threats, particularly during times of war. These fortifications include coastal defenses, bunkers, and artillery placements, primarily established during the late 19th and early 20th centuries. Notable examples include the Sydney Harbour Fortifications and the Fort Nepean in Victoria, which were designed to protect key ports and cities. The development of these fortifications was influenced by Australia's strategic location and the need to safeguard against naval attacks. Many of these sites are now preserved as historical landmarks, offering insights into Australia's military history and the evolution of defense strategies over time.