Modern Makeover for a Historic Sydney Fort

By Tara Chilcott

September 28, 2021

With its iconic sandstone construction and imposing Martello tower, Fort Denison is a key part of the historic fabric of Sydney Harbour. Today, it is a popular tourist attraction and a prime location to view Sydney’s iconic New Year’s Eve fireworks display, however Fort Denison has played many fascinating roles, including fortress, prison and maritime navigation hub.

Known to the Aboriginal people as Muddawahnyuh, the prominent rock island was first used by Europeans as a place of detention and was known as Pinchgut Island. The island was a prime location for a proposed harbour defence installation in the 1830s. In 1840, under Captain George Barney, work began on levelling the island and creating a terreplein and parapet for a gun battery. It was discontinued in 1843, but after further inquiry, work recommenced in the 1850s (again under Barney, by now a Lieutenant-Colonel, and Sir William Denison, Governor) to construct a battery with an associated barracks and Martello tower. The fort was named Fort Denison in 1857 and completed in 1862, with the construction of two flanking rooms to protect the fort on the northwest side.  The iconic Martello tower is the only one of its kind in Australia and was the last one built by the British Empire. Eight thousand tonnes of sandstone from nearby Kurraba Point was used in its construction. The fort was used for gunnery practice until 1876, and its military role appears to have ceased around that time, apart from a brief period of reoccupation by the army for anti-aircraft gunnery during World War II.

Fort Denison has been part of the navigation system for Sydney Harbour since 1858 (when a navigation light was placed on the tower) and a place for tide measurements since 1865. These functions continued under the Sydney Harbour Trust, which took over the island in 1903. A lightkeeper had been resident on the island since the 1870s, and the barracks block was progressively adapted for the caretaker’s residence during the first decade of the 20th century. In 1905, the island also became the site for the one o’clock gun, fired in conjunction with the descent of the time ball on Sydney Observatory to allow ships to check their chronometers.

Today, the island is part of the Sydney Harbour National Park and is currently undergoing a significant wharf upgrade. This includes the construction of a new loading bay wharf, extending out from the slipway on the northwest side of Fort Denison, replacing the current 1940s-era timber wharf.

The Cosmos Archaeology team conducted an underwater inspection in December 2020, and in January and May 2021, to assess whether any cultural heritage features could be impacted by piling works during the wharf’s construction. The seabed closest to the fort consisted primarily of a rocky rubble batter with a heavy covering of kelp and other marine growth. This gradually became sandier as the seabed sloped away from the fort.

Overall, the dive inspection identified very few items of maritime cultural heritage, although there is the potential for some archaeological remains to be within the area associated with the use and occupation of the fort, which would be of local cultural heritage significance.

As part of the project, Cosmos Archaeology also devised a Maritime Archaeological Management Plan to provide mitigation measures for the project, and to provide advice in the event of an unexpected find.