Fort Denison

In 1841, Captain George Barney levelled a 25 m high rocky island in Sydney Harbour for construction of a gun battery.

Construction of the Martello Tower and barrack block on the island from 1855 to 1857 was prompted by fear of a Russian naval attack during the Crimean War. It was designed by now, Lieutenant Colonel George Barney and was constructed by William Randle. The fort took its name from Sir William Thomas Denison, the Governor of New South Wales from 1855 to 1861.

The Martello tower is the only one ever built in Australia and the last one ever constructed in the British Empire. The fort is of national significance as an exceptionally fine and intact example of a 19th century defence fortification that is unique within Australia; it is one of only three towers in the southern hemisphere that survive intact; and forms part of a worldwide group of similarly styled and dated European coastal fort towers built during this period.

Fort Denison is the location of the State’s principal tide gauge since the 1870s, and has been an integral part of the Sydney Harbour navigation system since 1858. The island was the location for the time gun – that signaled time to the town, from 1906 to 1942; firing was re-introduced in 1986 as a tourist attraction and has been maintained since.