Huge crowds packed the steps for a distinctively Australian performance on the glittering harbourfront, where three generations of Danish architect Jorn Utzon's family were the guests of honour.
It was a postcard-perfect day beneath the same cloudless blue skies that inspired Utzon's winning design to build Sydney an opera house back in 1956 - the white sails drawn from his childhood in the Aalborg shipyards.
"A building like this happens once in a lifetime," Utzon's son Jan told revellers today.
A crew of surf lifesavers wearing their famous yellow-and-red caps and costumes arrived at the Opera House's Man O' War steps on one of Sydney's distinctive ferries, flanked by six of the association's dinghies and two tugboats.
More From This Section
They were met and led up the red-carpeted steps by Aboriginal dancers where a traditional smoking ceremony was held to spiritually cleanse the site accompanied by an indigenous dance ritual and didgeridoo.
A giant cupcake topped with a model of the Opera House made from icing was carried onto the stage by the lifesavers, and Australian rocker Jimmy Barnes - frontman of Cold Chisel - led a rousing chorus of Happy Birthday accompanied by a navy brass band and school choir.
The distinctive performance hall is one of Australia's best-known landmarks and centrepiece of Sydney's cultural scene, hosting some 2,000 shows every year and attracting 8.2 million visitors.
"As the most internationally recognisable symbol of both Sydney and Australia, it has become our calling card to the world," said Governor of New South Wales, Marie Bashir.
Opera House chief Louise Herron said the huge crowds were a reminder "that the Opera House is, above all, the people's palace."
Utzon won an international design contest to build the harbour city an opera house in 1956 that attracted 233 entries from 28 countries, despite being relatively unknown in the architecture world.