The waters near Sydney, Australia, are home to a variety of aids to navigation, but one of the most striking is the light atop Fort Denison, a sandstone fortress completed in the heart of the harbor in 1862 to guard the area from foreign attack. Before its military use that ended in the 1870s, the island also served as a prison for some years. Fort Denison is now part of Sydney Harbour National Park and is administered by the New South Wales National Parks and Wildlife Service (NPWS).

The Martello Tower at one end of the fort was one of the last of its type to be constructed in the world. The lantern and light were added in 1913 at the tower's summit, replacing an eight-inch gun in that location. The light was originally fueled by acetylene gas and was converted to electricity by 1926. The fort is still an important navigational facility, with a tide gauge, navigation channel markers, and a foghorn in addition to the light.

After 90 years of service as a guide for shipping in the harbor, the lightroom structure was removed for renovation on October 30, 2003. A helicopter transported the lantern to shore in a sling, and it was later taken to a workshop at nearby St. Peters. National Parks, Sydney Ports Corporation and Australian Defence Industries coordinated the operation. NPWS curator Stephen Thompson said the airlift was the safest way to move the lantern.

According to Anne Cummins of Sydney Artefacts Conservation, the base of the lantern was heavily corroded. The corrosion had pervaded the iron plate around the base of the lantern, perforating the metal and leaving the lighthouse structurally unsound. Rampant corrosion was also found in many of the other metal parts of the structure. Conservation treatment proceeded in several stages.

The structure was partially disassembled and layers of paint were removed. After chemical analysis of all the metals, the iron plate was removed and new steel patches were welded onto the corroded areas. A new replica base ring was fabricated to replace the old one, which was beyond repair. The replica was hot riveted into place by blacksmiths, a method rarely used today.

After the corrosion was removed, all the surfaces were repainted and the exterior was treated to prevent further corrosion. Finally, the lantern was returned to the fort by helicopter and reinstalled on May 20, 2004, with plenty of attention paid by the local media. Much of the fort is open to public tours, and there's even a café inside. The fort has been managed by NPWS since 1992, and they've put over $2 Million (Australian dollars) into its maintenance.