Under the direction of Dr John Bradfield of the NSW Department of Public Works, the bridge was designed and built by British firm Dorman Long and Co Ltd of Middlesbrough and opened in 1932. The bridge's design was influenced by the Hell Gate Bridge in New York City.
It is the sixth longest spanning-arch bridge in the world and the tallest steel arch bridge, measuring 134 m (440 ft) from top to water level. It was also the world's widest long-span bridge, at 48.8 m (160 ft) wide, until construction of the new Port Mann Bridge in Vancouver was completed in 2012.
The Sydney Harbour Bridge was added to the Australian National Heritage List on 19 March 2007 and to the New South Wales State Heritage Register on 25 June 1999.
The bridge was formally opened on Saturday, 19 March 1932. Among those who attended and gave speeches were the Governor of New South Wales, Sir Philip Game, and the Minister for Public Works, Lawrence Ennis. The Premier of New South Wales, Jack Lang, was to open the bridge by cutting a ribbon at its southern end.
According to wikipedia