The ArcelorMittal Orbit (often referred to as the Orbit Tower or its original name, Orbit) is a sculpture and observation tower in Queen Elizabeth Olympic Park in Stratford, London. It is Britain's largest piece of public art,Tim Adams: "Anish Kapoor's Orbit tower: the mother of all helter-skelters" in The Guardian, 5 May 2012 and is intended to be a permanent lasting legacy of London's hosting of the 2012 Summer Olympic and Paralympic Games, assisting in the post-Olympics regeneration of the Stratford area. Sited between London Stadium (formerly called the Olympic Stadium) and the Aquatics Centre, it allows visitors to view the whole Olympic Park from two observation platforms.

Orbit was designed by Turner Prize–winning artist Anish Kapoor and Cecil Balmond of Arup Group, an engineering firm. Announced on 31 March 2010, it was expected to be completed by December 2011. The project came about after Mayor of London Boris Johnson and Olympics Minister Tessa Jowell decided in 2008 that the Olympic Park needed "something extra". Designers were asked for ideas for an "Olympic tower" at least high: Orbit was the unanimous choice from proposals considered by a nine-person advisory panel. Kapoor and Balmond believed that Orbit represented a radical advance in the architectural field of combining sculpture and structural engineering, and that it combined both stability and instability in a work that visitors can engage with and experience via an incorporated spiral walkway. It has been both praised and criticised for its bold design, and has especially received criticism as a vanity project of questionable lasting use or merit as a public art project.

The project was expected to cost £19.1million, with £16million coming from Britain's then-richest man, the steel tycoon Lakshmi Mittal, Chairman of the ArcelorMittal steel company, and the balance of £3.1million coming from the London Development Agency. The name "ArcelorMittal Orbit" combines the name of Mittal's company, as chief sponsor, with Orbit, the original working title for Kapoor and Balmond's design.

The ArcelorMittal Orbit temporarily closed after the 2012 Olympic and Paralympic Games while the South Plaza (in which Orbit is positioned) underwent reconstruction for its long-term legacy use as a public outdoor space. It re-opened to the public on 5 April 2014. The structure incorporates the world's tallest and longest tunnel slide, designed by Carsten Höller. The idea was originally envisioned by the London Legacy Development Corporation as a way to attract more visitors to the tower. The slide includes transparent sections to give a "different perspective" of the twisting red tower and was completed in June 2016. This follows an option to abseil down the tower, introduced in 2014.

History According to London mayor Boris Johnson, in around October 2008 he and Tessa Jowell decided that the site in Stratford, London that was to become the Olympic Park for the 2012 Olympics needed "something extra" to "distinguish the East London skyline", and "arouse the curiosity and wonder of Londoners and visitors".

A design competition held in 2009 called for designs for an "Olympic tower". It received about 50 submissions. Johnson has said that his early concept for the project was something more modest than Orbit, along the lines of "a kind of 21st-century Trajan's Column", but this was dropped when more daring ideas were received.

The media reported unconfirmed details of the project in October 2009, describing the interest of the steel magnate Lakshmi Mittal, one of Britain's richest men, in funding a project that would cost around £15million. Boris Johnson was believed to want something like the Eiffel Tower or the Statue of Liberty. At that time there were understood to be five artists being considered, including Antony Gormley. Early designs reportedly included 'Transmission' by Paul Fryer, a high structure "resembling a cross between a pylon and a native American totem pole", according to The Times. A spokesman for Johnson would only confirm that he was "keen to see stunning, ambitious, world-class art in the Olympic Park", and that work on commissioning the project was at an early stage.

Mittal's involvement came about after a chance meeting with Johnson in a cloakroom in Davos in January 2009, as they were on their way to separate dinner engagements. In a conversation that reportedly lasted 45 seconds Johnson pitched the idea to Mittal, who immediately agreed to supply the steel. Mittal later said of his involvement, "I never expected that this was going to be such a huge project. I thought it was just the supply of some steel, a thousand tonnes or so, and that would be it. But then we started working with artists and I realised that the object was not just to supply steel but to complete the whole project. It took us almost 15 months of negotiation and discussion." Johnson has said that, "In reality, ArcelorMittal has given much more than the steel."

Kapoor's and Balmond's Orbit was announced as the winner on 31 March 2010. According to The Guardian, Orbit was chosen from a short list of three, beating a design by Antony Gormley and one by the architectural firm Caruso St John. According to The Times, Gormley's design was a steel colossus titled Olympian Man, a trademark piece of a statue of himself, rejected mainly on the grounds of its projected cost, estimated at £40million.

Johnson and Jowell agreed to issue a commission for Orbit in partnership with Mittal after it was chosen by a nine-person advisory panel brought together by them to advise on a long list of proposals. According to Mittal, the panel made a unanimous decision to pick Orbit, as it both represented the Olympic Games and was achievable within the ambitious time frame. Kapoor described it as "the commission of a lifetime".

Johnson pre-empted possible criticism during the official launch by stating: "Of course some people will say we are nuts – in the depths of a recession – to be building Britain’s biggest ever piece of public art. But both Tessa Jowell and I are certain that this is the right thing for the Stratford site, in Games time and beyond."

The completed structure was officially unveiled to the press and public on 11 May 2012.

An image of the structure was included in the 2015 design of the British passport.

The structure was re-purposed with the world's longest slide in 2016, as a way to attract more visitors.

Design

Interpretation According to Kapoor, the design brief from the Mayor's office was for a "tower of at least ", while Balmond said that he was told the Mayor was "looking for an icon to match the Eiffel Tower".

Kapoor said that one of the influences on his design was the Tower of Babel, the sense of "building the impossible" that "has something mythic about it", and that the form "straddles Eiffel and Tatlin". Balmond, working on the metaphor of an orbit, envisaged an electron cloud moving, to create a structure that appears unstable, propping itself up, "never centred, never quite vertical". Both believe that Orbit represents a new way of thinking, "a radical new piece of structure and architecture and art" that uses non-linearity – the use of "instabilities as stabilities." The spaces inside the structure, in between the twisting steel, are "cathedral like", according to Balmond, while according to Kapoor, the intention is that visitors will engage with the piece as they wind "up and up and in on oneself" on the spiral walkway.

The Independent described Orbit as "a continuously looping lattice ... made up of eight strands winding into each other and combined by rings like a jagged knot". The Guardian describes it as a "giant lattice tripod sporting a counterweight collar around its neck designed to offset the weight of its head, a two-storey dining and viewing gallery". According to the BBC, the design incorporates the five Olympic rings.

Upon its launch Johnson said "It would have boggled the minds of the Romans. It would have boggled Gustave Eiffel." Nicholas Serota, a member of the design panel, said that Orbit was a tower with an interesting twist, with "the energy you might traditionally associate with this type of structure but in a surprisingly female form".

According to Mittal, Orbit was already the working title, as it describes continuous action, a creative representation of the "extraordinary physical and emotional effort" that Olympians undertake in their continuous drive to do better. It was decided to keep this as the final name and prepend ArcelorMittal (as the project supporter).

On the public announcement of the design Johnson conceded that it might become known by something other than its official name, suggesting "Colossus of Stratford" or the "Hubble Bubble", in reference to his belief that it resembles a giant shisha pipe, or a variant on people's perceptions that it resembled a "giant treble clef", a "helter-skelter", or a "supersized mutant trombone".

Designers Orbit is described as "designed by Anish Kapoor and Cecil Balmond". Kapoor is a Turner Prize winning sculptor, while Balmond is one of the world's leading designers. According to Kapoor, both men are "interested in a place where architecture meets sculpture" and "the way that form and geometry give rise to structure". Kapoor and Balmond stated that their interests have blurred and crossed over into each other's fields since they first began working together in 2002 on Kapoor's Marsyas installation in the Turbine Hall of the Tate Modern. As well as Orbit, in 2010 Kapoor and Balmond were also working on the Tees Valley Giants, a public art project in northern England.

The sculpture was engineered by the Global engineer Arup, who developed the overall geometry, structural design and the building services including the lighting displayed extensively during the Olympic games. Architectural input by Kathryn Findlay (Ushida Findlay Architects, as a sub-consultant to Arup) made the sculpture into a functional building, for example designing the staircase.

Structural

The organic design of Orbit demanded an extraordinary amount of structural engineering work. This was done by Arup, which reported that it took up two-thirds of the budget for the project (twice the percentage normally allotted to structural engineering in a building project).

From a structural point of view, Orbit consists of two parts: the trunk – the more-or-less vertical tower which houses the elevators and stairs and supports the observation deck. the red tube – an open lattice of red steel that surrounds the trunk.

The trunk has a base diameter of , narrowing to on the way up, then widening again to just under the observation deck. The trunk is supported and stabilized by the tube, which gives a structural character of a tripod to the entire construction. Further structural integrity is given to the construction by octagonal steel rings that surround the tube and trunk, spaced at and cross-joined pairwise by sixteen diagonally mounted steel connectors.

A special part of the construction is the canopy, the conic shape that hangs off the bottom of the trunk. Originally planned as a fibreglass composite construction, costs forced the use of steel for this section as well. Centraalstaal was approached as a special consultant for the design of the steel cone and came up with a design for a cone built out of 117 individually shaped steel panels with a total surface area of 586 square metres. The entire cone weighs 84 tonnes.

Height Early contradictory reports suggested the tower would be tall. However, it finally measured in at , making it the UK's tallest sculpture, surpassing the tall Aspire in Nottingham.