The 2012 Summer Olympics and Paralympics cauldron was used for the Olympic flame during the Summer Olympics and Paralympics of London 2012. The cauldron was designed by Thomas Heatherwick and described as "one of the best-kept secrets of the opening ceremony": until it was lit during the Olympics ceremony, neither its design and location, nor who would light it, had been revealed.^[1] For the Olympics it consisted of 204 individual 'petals', and for the Paralympics 164, one for each competing nation.^[2]

British designer Thomas Heatherwick was chosen by Danny Boyle to design the cauldron for the 2012 London Summer Olympics and Paralympic Games (the same design would serve both).^[3] Heatherwick was a highly regarded designer, responsible for the first prize-winning "Seed Cathedral" at the 2010 Shanghai Expo, and the New Routemaster bus introduced in London in February 2012;^[4] Boyle was an admirer of his B of the Bang sculpture in Manchester, saying of it 'I loved it so much; it's a tragedy they took it down in 2009 ... These public sculptures breathe life into you.'^[3][5]

The brief was that the cauldron should be something that connected all the nations, with the idea of them each bringing a constituent part of it, and also have a story or narrative. It was to be of a human scale, and to be placed among the people in the stadium rather than towering over it. It was also to be transient, like the coming-together of nations during each Games.^[6]

Heatherwick said “When Danny Boyle asked us to do this we felt this huge responsibility. We asked people: ‘Which cauldron do you remember?’ And the answer was: none. Our role was to design a 'moment': how could we make this moment manifest in the object? We didn't just want to make a bowl on a stick.”^[4] He was also keen to avoid the competitive aspect of designs for the previous Olympics: "We were aware that cauldrons have been getting bigger, higher and fatter as each Olympics has happened and we felt that we shouldn't try to be even bigger than the last ones."^[7] Heatherwick and his team spent two months researching and examining ideas, including a weekend spent looking at all previous Olympic cauldron designs.^[8]

Another important part of the brief was "Whatever you do, no moving parts". This was due to the failure of the cauldron at the 2010 Winter Olympics at Vancouver, when one of the four moving parts of the cauldron had failed to work.^[3] Heatherwick said “When we proposed the most moving parts ever in an Olympic cauldron, we were nervous and feeling a bit guilty about that. But the same man who’d said that to us was the first person to say yes.”^[9]

Heatherwick wanted the cauldron to be a focal point, like an altar in a church,^[4] and he described it as symbolising "the coming together in peace of 204 nations for two weeks of sporting competition ... a representation of the extraordinary, albeit transitory, togetherness that the Olympic Games symbolise"^[7][10] The Olympic cauldron comprised 204 separate copper 'petals', and the Paralympic one 164 – one petal from each of the competing nations.

Production began in January 2012 in the workshops of Tockwith, near Harrogate-based firm Stage One.^[11] Each 3mm thick petal was unique: designed individually using 3D modelling, hand beaten from copper sheeting, and polished by skilled craftsmen.^[7][12][13] Each was hand-beaten over its own individual MDF former and took eight hours to produce.^[14] The petals were inscribed with the name of the competing country and "The XXX Olympiad – London 2012".^[15] Three full sets were made: for Olympic and Paralympic cauldrons, with a third for rehearsals and testing.^[13] The work on the cauldron at Stage One took 25,000 man hours.^[11]

The cauldron measured 8.5 metres high, 8 metres across when flat on the ground, and weighed 16 tonnes. It was significantly smaller and lighter than those of previous Games: the Beijing 2008 Summer Olympics cauldron weighed 300 tonnes.^[13] The cauldron burned natural gas,^[16] with a variable burn rate.^{[citation needed]} The gas burners were designed by Australian firm FCT Flames based in Adelaide, which specialises in the design, manufacture and operation of ceremonial cauldrons around the world.The firm became a partner of the International Olympic Committee shortly after the 2000 Summer Olympics and became responsible for manufacturing the fuel in which the Olympic flame burns during the relay and in many cases was responsible for the construction and elaboration of the Pyre that burned during the 16 days of the Olympic Games and 12 days of the Paralympic Games in the host city. ^[7] The mechanical and electrical engineering of the cauldron was complex and demanded the most time of the project, due to the large number of moving parts. 15 km of wiring went into the control panels and another 5.5 km into the cauldron itself.^[17]

Strict security and secrecy was paramount during construction and testing. During the project's first phase, which consisted of elaboration, assembly and first tests, the structure gained the nickname of "Betty" (This name comes after the dog of the opening ceremony's executive producer Catherine Ugwu).^[18] Initial testing took place at Stage One's workshop, which was screened to hide it from public view.

The cauldron was installed in the centre of the arena of the Olympic stadium using a 500-ton crane. This was done during overnight on 10 June 2012, in order to maintain the greatest secret of the opening ceremonies.^[19] All the tests and rehearsals were held at late night or early morning during the time that the Olympic airspace restrictions were in place, which stopped civil helicopters or planes from getting a view and take photos ^[20] During the final rehearsal on the eve of the Opening Ceremony,parts of the cauldron failed; this news was deliberately withheld from Heatherwick.^[21] Despite all this secrecy, the cauldron was "cheekily hidden in plain sight",as the images of the sketches are printed on the ceremony tickets.^[22]

The cauldron received overwhelmingly positive reviews. The London Evening Standard called it "breathtakingly beautiful",^[38] while a reviewer for The Daily Telegraph commented that "It dazzles both by its exuberance and inventive dexterity".^[16] The Guardian said it was "surely one of the most enduring images of London 2012 ... the drawing together of 204 long-stemmed and flaming petals seemed to prompt a collective gasp of delight across the UK – for its symbolism as well as its technical grace."^[39] Creative Review said "From the moment it was lit to its last flicker, Heatherwick Studio's cauldron was an absolute star of the Games. Conceptually brilliant and utterly beautiful it was one of the most successful examples of an ambition among the Games' organisers to reinvent the familiar elements of the Olympics."^[40] A reviewer for the Sydney Morning Herald called the cauldron "stunning".^[41]

An end of year review chose the cauldron as one of the top five design highlights of 2012,^[47] and Heatherwick was voted the Architects' Journal architecture personality of 2012 by its readers.^[48] On 12 March 2013 it was announced that the cauldron had won the Visual Arts category of the 2012 South Bank Sky Arts Awards.^[49][50][51] The cauldron was shortlisted for the Design Museum's 'Designs of the Year 2013' Awards in the 'Product' category.^[52]

• 2008 Summer Olympics cauldron
• 2010 Winter Olympics cauldron
• 2012 Summer Olympics opening ceremony
• 2012 Summer Olympics closing ceremony
• 2012 Summer Paralympics opening ceremony
• 2012 Summer Paralympics closing ceremony
• 2014 Winter Olympics cauldron
• 2016 Summer Olympics cauldron

Sequence showing the cauldron starting to open out before it is extinguished at the 2012 Summer Olympics closing ceremony.