The Beehive Casemate is an historical fortification located on the banks of Obelisk Bay, in Sydney Harbour. Construction began in 1871 and was completed in 1874. The fort was constructed under the supervision of colonial architect James Barnet

James Barnet

James Johnstone Barnet was the Colonial Architect for New South Wales from 1862 - 1890.-Life and career:Barnet was born at Almericlose, Arbroath, Scotland. The son of a builder, he was educated at the local high school...

. The underground Casemate was one of the first to be locally designed and built after the withdrawal of British troops in 1870 and the Cardwell Reforms

Cardwell Reforms

The Cardwell Reforms refer to a series of reforms of the British Army undertaken by Secretary of State for War Edward Cardwell between 1868 and 1874.-Background:...

. The fortification contains three domed chambers that were used as gun emplacements, each chamber had a small opening or window for the gun to fire through with each window looking out towards the Sydney Heads

Sydney Heads

Sydney Heads , is the entrance to Port Jackson in Sydney, New South Wales, Australia.North Head and Quarantine Head are to the north, South Head and Dunbar Head are to the south. Middle Head, Georges Head and Chowder Head are to the west and within the bay...

. The underground chambers were made of brick and mortar and were built into the excavated cavities in the sandstone bedrock. They were intended to fire on enemy ships as they navigated the passages around Sow and Pigs Reef, within the entrance to Sydney Harbour.