Sydney Opera House serenades Danish architect's 90th birthday

Staff at the Sydney Opera House this month sang 'Happy Birthday' to Jorn Utzon, the Danish architect who created the famous harbourside building, to celebrate his 90th birthday.

The Sydney Symphony Orchestra played as about 250 staff gathered in the concert hall of the white-tiled, sail-shaped building Utzon designed half a century ago but which he has never seen completed. Utzon began work on the Opera House in 1957 but quit in 1966 following a storm of controversy over budget blow-outs and his artistic vision.

Before it opened in 1973, critics had likened the white sails of the now world-renowned building to 'albino turtles mating' and 'nuns packing into a scrum'.

Utzon, who lives in Denmark, renewed his involvement with the Opera House in 1999 after he was asked to work on refurbishing the interiors, most of which are not how he designed them and are acknowledged to have inadequate acoustics.

Opera House chief executive Richard Evans said staff wanted to celebrate Utzon's milestone birthday in a special way given his connection to the building.

'The relationship between the man and the building has extended for more than 50 years and Jorn is still adding to its potential,' he said.