Underground tunnel, North Fort, North Head Sanctuary, Manly (2020)

Strategically placed at the northern entrance to Sydney Harbour, North Fort was part of a defence system that spanned 300km of coastline during World War II.The once active army base previously featured 9.2 inch calibre guns, capable of firing a distance of 26km. Each heavy weapon was operated by nine soldiers with support from personnel running the underground shell and engine rooms.