Well before the sails of the Sydney Opera House were complete, architect Jorn Utzon was already thinking about how to decorate the inside of the building.

Now almost 60 years later, one of the artworks he commissioned is finally on display.

The Sydney Opera House has publicly unveiled the Utzon/Le Corbusier tapestry — a work of art that Opera House chief executive Louise Herron described as a "collaboration between two of the 20th century's greatest architects for one of the 20th century's greatest buildings".

"In 1958 Jorn Utzon wrote to Le Corbusier to ask if he would like to help with the decoration of the Opera House, as he put it, and the result was this tapestry," Ms Herron told the ABC.

At the time, Mr Utzon was a bold, young Danish architect whereas Le Corbusier was a well-renowned French-Swiss architect who was coming to the end of his career.

"Apparently the reason the tapestry is called Les Des Sont Jetes (The Dice Are Cast) is because when Le Corbusier saw Mr Utzon's design he thought 'this is the future of architecture'.

"[Le Corbusier] was so inspired by what he saw that he decided he would collaborate [with Mr Utzon], which is not something he usually did."

The tapestry will hang in the Western Foyer of the Opera House, an interior that was designed by Mr Utzon.

"It injects the Utzon DNA back into the building — as you know Utzon left before the Opera House was complete ... [but] this is an original Utzon intention to have this tapestry at the Opera House."

Tapestry rescued before auction in Denmark

The Les Des Sont Jetes was woven in France, but after Mr Utzon famously resigned from the Opera House project in 1966 it never made its way to Sydney.

It was due to be auctioned last year until Ms Herron was sent to rescue it, at the insistence of philanthropist Peter Weiss.

Sydney Opera House CEO Louise Herron says the tapestry was oily from hanging in a Danish kitchen when it arrived. ( ABC News )

"I said 'it mustn't go for auction, you must buy it' and Louise said 'how?' and I said 'get on a plane just do it'," Mr Weiss told the ABC.

"I said 'I'll put some money towards it and find other donors - it has to be bought, it has to come back home'."

Long-time arts supporter Mr Weiss contributed the most money, but funds also came from other philanthropists, Opera House staff and the New South Wales Government.

Despite the $400,000 price tag, the tapestry was a little worse for wear after decades hanging in the Utzon family dining room in Denmark.

Once it arrived in Sydney, Julian Bickersteth from International Conservation Services and his team were tasked with restoring it.

"Tapestries and food don't go terribly well together so there was a fair bit of splatter all over it," Mr Bickersteth said.

"I don't think it had ever been cleaned in that time, it might have been lightly brushed down, but the challenge was to how safely to clean it to bring back the vibrancy of those incredible colours.

"That is a process that means literally putting it in a bath, but you can't do that until you have tested the colours to check none of them are going to run, and then you have to have the right PH of the detergents and the water we're using to ensure they stay locked in."

A visitor to the Western Foyer of the Sydney Opera House admires the new Les Dés Sont Jetés (The Dice Are Cast) tapestry. ( ABC News: Mazoe Ford )

Seeing the Les Des Sont Jetes hanging in the Opera House for the first time was a particularly proud moment for Antony Moulis from The University of Queensland's School of Architecture.

Without his research, it might never have happened.

"I discovered letters in 2006 at the Le Corbusier archive in Paris describing the commission that Utzon asked Le Corbusier to design this tapestry work for the Opera House," Dr Moulis said.

"It was a commission that very little was known about and I thought it was a commission that should be more well known.

"As I researched the letters I discovered that the work had been made in 1960 and sent to Utzon in Denmark, so it was a very exciting discovery."