2 Best Sights in Sydney Harbour, Sydney

For a brief time in the early days of the colony, convicts who committed petty offenses were kept on this harbor island, where they existed on such a meager diet that the island was named Pinchgut. Fortification of the island was completed in 1857, when fears of Russian expansion in the Pacific spurred the government on. Today the firing of the fort's cannon doesn't signal imminent invasion, but merely the hour—one o'clock. New South Wales National Parks and Wildlife Service runs half-hour tours at Fort Denison.

Although it's still known as an "island," this promontory was connected with the mainland in 1942. During the 1941–45 War of the Pacific (WWII and a number of preceding conflicts), Australia's largest naval base and dockyard was a frontline port for Allied ships. Part of the naval base is now open to the public. Access, seven days a week, to the site is via ferry from Circular Quay (take the Watsons Bay ferry). Visitors can view the museum and picnic on the hill. The Naval Historical Society runs tours to the "secure" section of Garden Island but these must be booked well in advance. The 90-minute tours run every Thursday.