The Harbour Control Tower was built to oversee shipping movements in and out of Port Jackson. It became operational in 1974, after the conversion of the finger wharves at Darling Harbour into longshore roll-on/roll-off container terminals.
It consisted of a reinforced concrete column with an internal lift, topped by stainless steel and glass observation and operations areas.
The reinforced concrete base of the tower was 7.6m in diameter by 2.9m deep with connected plant and pump rooms and emergency equipment storage. Foundations were embedded into rock and rock anchors penetrated 7.9m to provide adequate anchorage. A circular reinforced concrete shaft 4.9m in diameter rose from the base; housing lift, stairs and ducting for services.
The three upper floors were 10m in diameter and were cantilevered from the shaft, while the roof framework was 15.2m in diameter. Wind loading was a critical factor in designing the tower.