Fort Denison, part of the Sydney Harbour National Park, is a protected national park that is a heritage-listed former penal site and defensive facility occupying a small island located north-east of the Royal Botanic Garden and approximately 1 kilometre (0.62 mi) east of the Opera House in Sydney Harbour, New South Wales, Australia.

He said to the hangman that the only thing worth mentioning was the superb view of the harbour from his high elevation, and that he was sure there were no waters the world over to compare with it for beauty.

The newly built fort then took its current name from Sir William Thomas Denison, the Governor of New South Wales from 1855 to 1861.

In 1913 a lighthouse beacon built in Birmingham, England, and shipped to Sydney, replaced the 10-inch (250 mm) gun on the roof of the tower.

When the US Navy cruiser USS Chicago fired on the Japanese, some of its 5-inch (130 mm) shells hit Fort Denison, causing the tower minor damage which remains visible.

In October 1900, as the Boer war raged in Africa, the White Star Line ship SS Medic sailed into Sydney Harbour and dropped anchor in Neutral Bay.

One night, the fourth officer, Charles Lightoller and two shipmates rowed to Fort Denison and climbed the tower with a plan to fool locals into believing a Boer raiding party was attacking Sydney.

They hoisted a makeshift Boer flag on the lightning conductor and fired a harmless wad of cotton waste from one of the 8-inch cannons.

Since 1992, the NSW National Parks & Wildlife Service, which manages the site, has spent around A$2m conserving and upgrading the facilities.

Fort Denison is now a museum, tourist attraction, restaurant, and popular location for wedding receptions and corporate events.

Access to Fort Denison is via a ferry that departs Wharf 6 at Circular Quay every 45 minutes, 7 days a week.

The Bureau of Meteorology operates a weather facility from the island and publishes observations at half-hourly intervals on its website.

Fort Denison was the location of the 1959 film The Siege of Pinchgut, released in the United States as Four Desperate Men.

Directed by Harry Watt, written by Jon Cleary and starring Aldo Ray, the production was the final Australian film of the British-based Ealing Studios.

The island also featured as the base of operations for Neville Savage in the sixth episode of the Australian children's television show Mission Top Secret.

However, on close inspection the sandstone bedrock visible below the south west battery reveals part of the rock of the island, particularly when combined with the pictorial evidence provided by drawings such as that by Barrington in 1802.

[17] The Fort Denison photographs below show float activated tide gauge instruments in a cabinet and the system's stilling well.

[18] A wire connected to the upper drum mechanism passes out through the bottom right of the cabinet and runs over a pulley to drop down to the float system in the large pipe in the well.