Cloud Gate

One of the synonymous experiences with Chicago is visiting Cloud Gate, affectionately known as The Bean. This sculpture utilised state of the art metal fabrication technology to create a mirror-like effect on rounded surfaces at a large scale. Cloud Gate was created using computer technology to cut out 168 massive stainless-steel sheets into precise shapes which were then pieced together like a jigsaw and welded shut. This created a 12-foot-high central arch with an inner chamber. It is fortified using internal rings that connect a truss and act as the two points to apply the weight of the structure. Advanced technology in metal fabrication allowed the stainless-steel skin to be attached to the internal structure with flexible connectors, these allow the material to expand and contract in response to extreme weather changes in Chicago.

“What I wanted to do in Millennium Park is make something that would engage the Chicago skyline ... so that one will see the clouds kind of floating in, with those very tall buildings reflected in the work. And then, since it is in the form of a gate, the participant, the viewer, will be able to enter this very deep chamber that does, in a way, the same thing to one's reflection as the exterior of the piece is doing to the reflection of the city around.” Anish Kapoor.

Cloud Gate is 110 tonnes, 66 feet long, 42 feet wide and 33 feet high, making it a cultural highlight to the city and one of the world’s largest permanent outdoor art installations. It was inspired by liquid mercury, with the use of highly reflective stainless steel capturing the reflections of the city around it.

Cloud Gate was the result of a design competition and once the artist Anish Kapoor’s design was chosen, there were numerous concerns that the design was not possible to build. However eventually a solution was found, and issues concerning maintenance and upkeep were resolved thanks to the rain keeping the sculpture clean. Although the artist does not draw with computers, the design relied heavily on computer modelling to analyse its complex form. There were multiple concerns, from bird droppings to graffiti, to the extreme seasonal temperature changes in this area of the world. These were all factors that the construction team had to consider in the initial stages of design.

British engineering firm Atelier One provided the sculpture structural design and Performance Structures Inc were chosen to fabricate the structure due to their ability to produce almost invisible welds. The Bean was built on-site at its place of the permanent fixture due to the risks associated with transporting it long distances. Its weight was substantial and raised concerns on the thickness of the steel required to properly create the desired aesthetic of seamless reflection.

The contract for Cloud Gate states that the piece is expected to survive for 1000 years due to the sheer thickness and quality of the construction and materials used.