Proposals to cross Sydney Harbour began in 1814, when convict architect Francis Greenway pitched a bridge to Governor Lachlan Macquarie, and continued through a floating bridge idea in 1840 and design competitions in 1900 and 1902. Norman Selfe’s winning cantilever design was scrapped after a change of government in 1904. Chief engineer John Bradfield revived the project after World War I, with his confidential secretary Kathleen M. Butler running international correspondence and later setting up the project office in London at Dorman Long, the English firm awarded the contract in 1924. The steel arch, modeled heavily on New York’s Hell Gate Bridge, was detailed by Dorman Long’s engineers Ralph Freeman and Georges Imbault, and a public feud over credit ended with a brass plaque bolted to one of the granite columns.

Workers began the arch in late 1928, driving six million rivets by hand, and 16 men died during construction. The bridge became known as the iron lung for keeping thousands employed through the Depression. On March 19, 1932, as Premier Jack Lang prepared to cut the ribbon, Francis de Groot of the New Guard rode in on horseback in military uniform and slashed it with a sword, declaring the bridge open in the name of the king. The ribbon was retied and Lang cut it with the golden scissors used for New York’s Bayonne Bridge in 1931, before a crowd estimated at 300,000 to 1 million.

• Why the four granite-faced pylons carry no load and were built only to reassure the public
• About 250 stonemasons who relocated to Moruya to quarry 18,000 cubic meters of granite for them
• Red-hot rivets tossed to a catcher with a bucket, then shrinking as they cooled to clamp the steel plates together
• Two clergymen who accidentally rode a load-testing train across the day before the opening
• The Bradfield Highway’s status as a travelling stock route, the grit-blasting robots Rosie and Sandy, and the Aboriginal flag raised permanently in 2022