How the Sydney Opera House was built: Utzon's sketch, the shells nobody could build, the orange that solved them, the resignation, and 14 years and 14 times the budget

Architecture · 4 September 2026

The Sydney Opera House was built between March 1959 and October 1973 on Bennelong Point in Sydney Harbour to the design of the Danish architect Jørn Utzon, who won the 1957 competition with sketches of sail-like shells that no one, including Utzon and his engineers Ove Arup and Partners, knew how to build; it took four years and a dozen schemes to find that the shells could all be cut from the surface of a single sphere and built from precast concrete ribs, another six to build them and cover them in a million Swedish tiles, and a change of state government in 1965 to drive Utzon out in 1966, after which Australian architects finished the interiors, which are not his. It opened on 20 October 1973, fourteen years late, at a cost of 102 million Australian dollars against an estimate of 7, paid for by a state lottery; it is the most famous building of the 20th century, a World Heritage Site since 2007, and Utzon, reconciled with it in 1999, never returned to see it. Below: the competition, the shells and how they were solved, the construction, the tiles, the politics, the interiors, the opening, the numbers and the myths, with the building's style in Mid-century modern architecture.

The competition, 1956–57

Sydney had no concert hall, and in 1954 the conductor of its orchestra, Eugene Goossens, persuaded the premier of New South Wales, Joseph Cahill, to build one on Bennelong Point, a tram depot on the harbour beside the bridge; an international competition in 1956 drew 233 entries from 32 countries, and the jury of four, joined late by the American-Finnish architect Eero Saarinen, chose in January 1957 the entry of Jørn Utzon, 38, of Hellebæk in Denmark, who had built almost nothing and had never seen the site, working from naval charts. The story, told by the jury's Australian member, is that Saarinen arrived after the others had made a shortlist, went through the rejected pile, pulled out Utzon's sheets of freehand sketches of shell roofs on a podium, and said "Gentlemen, this is the first prize"; the drawings were schematic, with no structure, and the jury's report said the shells were "capable of becoming one of the great buildings of the world". Utzon's idea came from the harbour, from the sails, from Mayan platforms he had seen in Mexico and from the segments of an orange; the estimate was 3.5 million pounds and three years. Sydney Opera House.

The shells nobody could build, 1957–61

Utzon's shells were free curves, parabolas and ellipses drawn by hand, each different, and the engineers Ove Arup and Partners in London, given the job in 1957, spent four years trying to make them stand: as thin concrete shells, the form the drawings implied, they were too shallow and too pointed to work as shells and would have needed to be thick and heavy, and every scheme, of single shells, double shells, steel frames and ribs of varying curvature, needed each shell's formwork to be made separately, at a cost no one could bear. Meanwhile the state, wanting work to be seen before the 1959 election, made Utzon start the podium in March 1959, and the foundations and the concourse beams were built for shells whose weight was unknown; when the shell design changed the columns already built were too weak, and in 1963 they were blown up and rebuilt. In 1961 Utzon, or Arup's engineers, or both, depending on who tells it, found the answer: if every shell was a segment of the same sphere, of 75 m radius, then every rib of every shell had the same curvature, and could be cast in a few standard moulds and assembled like the peel of an orange, the shells becoming ribbed vaults of precast concrete rather than thin shells; Utzon showed it to the client with a sphere and a knife, and the geometry that made the building buildable also gave it its final shape, more pointed and taller than the sketches.

Building the shells and the tiles, 1963–67

• The ribs. 2,194 precast concrete segments, cast on site in the standard moulds, up to 12 tons each, were assembled into ribs fanning from the base of each shell and held on an erection arch, a curved steel truss designed by Arup's Jack Zunz and Hornibrook's engineers that moved along under the ribs as they were placed, then post-tensioned with steel cables through the segments so that each rib became one piece; the largest shell is 67 m high.
• The tiles. Utzon wanted a roof that would shine without glare, and designed with the Swedish firm Höganäs a tile of clay with a glaze that is glossy white with a matt cream, 120 by 120 mm, 1,056,006 of them, set into 4,253 precast "lids" of curved concrete on the ground and lifted onto the ribs so that the tiling was done at ground level and the joints are perfect; the tiles are self-cleaning in rain and have been washed twice.
• The glass walls. The open ends of the shells were closed with walls of glass hung from the ribs, in a design Utzon left and Peter Hall completed, of laminated glass in bronze frames, 2,000 panes.
• The contractor. Hornibrook, who had built the Harbour Bridge's approaches, with 10,000 workers over the years; the sails were finished in 1967 without a death from the shells, though 16 died on the project in all.

The politics and the resignation, 1965–66

Cahill died in 1959 and the Labor government that had backed Utzon lost the election of May 1965 to the Liberals under Robert Askin, whose minister for public works, Davis Hughes, had campaigned on the cost and took the project over as its client, questioning Utzon's fees, refusing to pay his invoices, demanding drawings for the interiors that Utzon said could not be produced until the plywood prototypes he was making were tested, and cutting him off from the contractors. In February 1966, owed 100,000 dollars and with his office unable to pay its staff, Utzon wrote to Hughes that he was forced to withdraw, expecting to be called back; Hughes accepted the resignation the same day, appointed a panel of Australian architects, Peter Hall, David Littlemore and Lionel Todd, to finish the building, and Utzon left Australia in April 1966 with his family, by a side exit at the airport to avoid the press, and never came back. A thousand people marched on Parliament for his return; Harry Seidler and other architects protested; Hughes was unmoved. Utzon's plywood interiors, of the halls as folded ceilings hung inside the shells, were abandoned, and Hall, who had never designed a theatre, spent a year studying halls and redesigned the inside.

The interiors and the opening, 1966–73

Hall's panel made the biggest change: Utzon had planned the major hall for both opera and concerts, with a stage and machinery already built, and the Australian Broadcasting Commission, which ran the orchestra, insisted on a concert hall of 2,800 seats, so the stage machinery was ripped out, the major hall became the Concert Hall, and the opera was moved to the smaller hall of 1,500 seats, with a pit too small and wings too narrow for grand opera, which is why the Opera House has never been a good opera house; the interiors are of Hall's design, in white birch and brush box timber, with the Concert Hall's ceiling of plywood rings and the "acoustic clouds" over the stage, and were finished in 1973. Queen Elizabeth II opened the building on 20 October 1973, with fireworks and the Sydney Symphony playing Beethoven's Ninth, and Utzon was not mentioned in the speeches; the first performance had been Prokofiev's "War and Peace" by the Australian Opera on 28 September. The cost was 102 million dollars, paid by the Opera House Lotteries, which ran from 1957 to 1975 and, after the kidnapping and murder of a winner's son in 1960, paid out to anonymous winners; the lottery paid it off in July 1975.

Reconciliation and since

• 1999. The Opera House Trust asked Utzon, 81, to set out design principles for the building's future and to redesign the interiors as they were altered; he agreed, working from Denmark with his son Jan, and the Utzon Room, a reception room with his tapestry, opened in 2004, his only interior in the building.
• 2003. Utzon received the Pritzker Prize, the citation calling the building "one of the great iconic buildings of the 20th century"; he received the keys to the city of Sydney in 2003 and an honorary doctorate, in absentia.
• 2007. World Heritage listing, the youngest building on the list and the only one listed in its architect's lifetime; Utzon died in November 2008, aged 90, without having seen the finished building.
• 2009–24. The western foyer and colonnade to Utzon's design, the renewal of the Concert Hall in 2017–22 with the stage rebuilt and the acoustics finally fixed, the Joan Sutherland Theatre's machinery replaced in 2017; the 50th anniversary in 2023.
• Use. 1,800 performances a year in seven venues, 1.4 million people at them and 10 million visitors around it; the Sydney Symphony, Opera Australia, the Australian Ballet and the Sydney Theatre Company.

The numbers

• Size. 183 m long, 120 m wide, 67 m high at the tallest shell; 1.8 hectares on a site of 5.8; the podium's 588 concrete piers to 25 m below sea level.
• Shells. 14, in three groups, of 2,194 precast ribs on a sphere of 75 m radius; 350 km of tensioned cable; 1,056,006 tiles in 4,253 lids; 2,000 panes of glass.
• Halls. The Concert Hall, 2,679 seats, with the world's largest mechanical organ, 10,154 pipes, finished in 1979; the Joan Sutherland Theatre, 1,507; the Drama Theatre, 544; the Playhouse, 398; the Studio, 280; the Utzon Room, 210; the Forecourt outdoors.
• Time. Competition 1957; construction March 1959 to October 1973, 14 years against 4 planned; shells 1963–67, interiors 1967–73.
• Cost. 102 million Australian dollars against 7 million estimated, 1,457 per cent over; about 1 billion today; paid by lottery by 1975.
• Workers. About 10,000 over the project; 16 deaths.
• Electricity. 645 km of cable; the building uses the power of a town of 25,000.

Versions and theories

• Saarinen pulled it from the rejects. The story is told by the jury's Australian member, Cobden Parkes, and by the Opera House itself; the jury minutes are lost, and the other jurors said all entries were seen. It is the story everyone tells and it may be true.
• Utzon solved the shells with an orange. Or Arup's engineers solved them with geometry and Utzon presented it with an orange; both sides claimed the spherical solution, and the credit is shared in the histories. The orange is in the building's museum.
• Utzon was sacked. He resigned, in a letter he expected to be refused; Hughes accepted it within hours and did not ask him back. Utzon called it a forced withdrawal; the government called it a resignation.
• The building cost 14 times the estimate. The estimate of 7 million was made in 1957 from sketches with no design; the final cost of 102 million included the interiors, the changes and fourteen years of inflation. The lottery paid it all and the state never spent a tax dollar.
• The acoustics were always bad. The Concert Hall's were criticised from 1973 and rebuilt in 2017–22 with new reflectors and a raised stage; the opera theatre's problems, the pit and the wings, are those of a hall built for concerts and used for opera.
• The sails are white. They are two shades, glossy white and matt cream, in a chevron pattern, so that the roof reads as white in sun and cream in shade and never glares; up close it is a mosaic.

The engineering that made the shells possible is described in how domes are built; the age's other concrete is in Brutalist architecture.

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