Thousands of people turned out Sunday for the celebration of the 40th anniversary of the Sydney Opera House, the iconic building designed by Danish architect Jørn Utzon and declared a World Heritage Site by UNESCO.

The celebration, which includes a series of events scheduled throughout the week, featured the entrance of a flotilla into the port, aboriginal dances and the distribution of 6,000 cupcakes to participants.

Rock singer Jimmy Barnes, accompanied by three generations of Utzon's family, sang "Happy Birthday" to the opera house.

The Sydney Opera House is a tribute to the Australian spirit and was a dream come true for its designer, Jan Utzon, the architect's son, said.

"It is a unique Australian expression of will and enthusiasm," Utzon told ABC. "Let's go do it in the kind of spirit which was so prominent in Australia back in the 60s."

Jørn Utzon began designing the Sydney Opera House in 1957 after winning an international contest.

The performing arts center in Sydney Harbor was not inaugurated until Oct. 20, 1973, due to a series of problems and cost overruns.

UNESCO declared the building a World Heritage Site in 2007, a year before the architect died at age 90. EFE