Denmark's Princess Mary and Prince Frederik were on hand to help celebrate the 40th anniversary of the Sydney Opera House on Sunday (October 27) evening.
The Sydney Opera House was designed by Danish architect Jørn Utzon and was formally opened on October 20 in 1973.
Architect Jørn Utzon died in Copenhagen in November 2008 at the age of 90. His son, Jan Utzon, was there to take part in the celebrations in his father's place.
Part of the festivities was the 40th anniversary concert, with numerous artists performing on stage outside the Sydney Opera House.
In 1956 the government of the Australian state of New South Wales (NSW) launched an international design competition with an independent jury. The criteria did not specify design parameters or set a cost limit. Jørn Utzon won and became the sole architect.
The design and construction of the Opera House's shell structure took eight years to complete. The development of the special ceramic tiles for the shells took more than three years.
It cost A$102 million ($98.7 million) to build the Opera House. The initially estimate was A$7 million ($6.7 million).
In 1966 arguments about cost, interior design, and the government withholding payments resulted in Utzon's resignation. Other architects completed the project and Britain's Queen Elizabeth II opened it in 1973.
Jørn Utzon was re-engaged as architect in 1999 to develop a guide for all future changes to the building.
Utzon received the Pritzker Prize, international architecture's highest honor, in 2004.