How do you put a price on a national icon - a building which has come to symbolise a nation? The Sydney Opera House called in the number crunchers, who declared that it will be worth A$4.6bn (£2.74bn) to the Australian economy over the next 40 years, taking into account everything from land value and ticket sales to its contribution to "national identity".
The trigger for the unusual accounting exercise was the Opera House's 40th birthday, which will be celebrated tomorrow with the help of rock stars, lifeguards and celebrity chefs - not to mention thousands of ordinary Australians, who cherish the institution, even if its birth was painful and mired in controversy.
Opened by the Queen on 21 October 1973, the modernist masterpiece on Sydney Harbour - with its distinctive roof resembling billowing sails - cost A$102m at the time.
Accountants calculated the world's busiest performing arts centre has injected around A$775m into the economy every year, both directly and by attracting tourists to Australia.
More than half of the 650 tourists surveyed for the report, from China, the United States, Britain and New Zealand, said the Opera House was their main reason for visiting Sydney.
Deloitte, which carried out the recent valuation, out its total worth to be Aus$4.6 billion, taking into account ticket and retail sales, its value as a tourism draw, and what the report called "intangible cultural, iconic and national identity value".
"When we're talking about brands, the Sydney Opera House is quite simply Australia's best," said Deloitte partner David Redhill.
According to the report, which surveyed 3000 people, visitors were prepared to pay 22 per cent more for tickets to an event if it was being held at the Opera House.
Among those attending the birthday celebrations will be Jan and Lin Utzon, children of the visionary Danish architect, Joern Utzon, who conceived the building after winning an international design competition.
Utzon never saw the completed work - "the ultimate people's palace", as one New South Wales premier called it - that brought him global acclaim. He was forced off the project in 1966 following a row with the NSW government about spiralling costs, and vowed never to return to Australia.
The rift was not healed until recent years, when the architect agreed to be principal design consultant on a major revamp. After he died in 2009, Australian politicians, dignitaries and artists celebrated his legacy at a state memorial service in the Opera House.
Placed on the World Heritage list in 2007, alongside the Taj Mahal, Pyramids and Great Wall of China, the Opera House played a significant role in the evolution of Australia's cultural identity. Writing in the Sydney Morning Herald yesterday, Lin Utzon said it changed "a whole nation's outlook and perception of itself".