Fort Denison is a small island located in Sydney Harbour, Australia. Originally built in the 1850s, it was designed to protect the city from potential naval attacks. The fort features a distinctive stone tower and was equipped with cannons, although it never saw combat. Today, Fort Denison is a popular tourist attraction and part of the Sydney Harbour National Park. Visitors can explore its historical significance and enjoy panoramic views of the Sydney Opera House and Sydney Harbour Bridge. The site also includes a museum that showcases its military history and the role it played in the defense of Sydney.