Cloud Gate
Cloud Gate is a public sculpture by Indian-born British artist Anish Kapoor, that is the centerpiece of Grainger Plaza at Millennium Park in the Loop community area of Chicago. Constructed between 2004 and 2006, the sculpture is nicknamed "The Bean" because of its shape, a name Kapoor initially disliked but later grew fond of. Made up of 168 stainless steel plates welded together, its reflective and highly polished exterior has no visible seams. It measures, and weighs. The sculpture and its plaza are located above Millennium Hall, between the Chase Promenade and McCormick Tribune Plaza & Ice Rink.
Kapoor's design was inspired by liquid mercury and the sculpture's surface reflects and distorts the city's skyline and clouds moving overhead. Visitors are able to walk around and under Cloud Gates high arch. On the underside is the "omphalos", a concave chamber that warps and multiplies reflections. The sculpture builds upon many of Kapoor's artistic themes, and it is popular with tourists as a photo-taking opportunity for its unique reflective properties.
The sculpture was the result of a design competition. After Kapoor's design was chosen, numerous technological concerns regarding the design's construction and assembly arose, in addition to concerns regarding the sculpture's upkeep and maintenance. Various experts were consulted, some of whom believed the design could not be implemented. Eventually, a feasible method was found, but the sculpture's construction fell behind schedule. It was unveiled in an incomplete form during the Millennium Park grand opening celebration in 2004, before being concealed again while it was completed. Cloud Gate was formally dedicated on May 15, 2006, and has since gained considerable popularity, both domestically and internationally.
Design
Lying between Lake Michigan to the east and the Loop to the west, Grant Park has served as Chicago's "front yard" since the mid-19th century. Its northwest corner, north of Monroe Street and the Art Institute, east of Michigan Avenue, south of Randolph Street, and west of Columbus Drive, had been Illinois Central rail yards and parking lots until 1997, when it was made available for development by the city as Millennium Park. In 2007, the park was Chicago's second largest tourist attraction, trailing only Navy Pier.In 1999, Millennium Park officials and a group of art collectors, curators and architects reviewed the artistic works of 30 different artists and asked two for proposals. American artist Jeff Koons submitted a proposal to erect a permanent sculpture of a playground slide; his glass and steel design featured an observation deck above the ground that was accessible via an elevator. The committee chose the second design by internationally acclaimed artist Anish Kapoor. Measuring and weighing, the proposal featured a seamless, stainless steel surface inspired by liquid mercury. This mirror-like surface would reflect the Chicago skyline, but its elliptical shape would distort and twist the reflected image.
In the underside of the sculpture is the omphalos, an indentation whose mirrored surface provides multiple reflections of any subject situated beneath it. The apex of the omphalos is above the ground. The concave underside allows visitors to walk underneath to see the omphalos, and through its arch to the other side so that they view the entire structure. During the grand opening week in July 2004, press reports described the omphalos as the "spoon-like underbelly". The stainless steel sculpture was originally envisioned as the centerpiece of the Lurie Garden at the southeast corner of the park. However, Park officials believed the piece was too large for the Lurie Garden and decided to locate it at what is now known as Grainger Plaza, despite Kapoor's objections. Skyscrapers to the north along East Randolph Street, including The Heritage, the Smurfit-Stone Building, Two Prudential Plaza, One Prudential Plaza, and Aon Center are visible, reflected on both the east and west sides of the sculpture.
Around the structure, its surface acts like a fun-house mirror as it distorts their reflections.
Although Kapoor does not draw with computers, computer modeling was essential to the process of analyzing the complex form, which created numerous issues. Since the sculpture was expected to be outdoors, concerns arose that it might retain and conduct heat in a way that would make it too hot to touch during the summer and so cold that one's tongue might stick to it during the winter. The extreme temperature variation between seasons was also feared to weaken the structure. Graffiti, bird droppings and fingerprints were also potential problems, as they would affect the aesthetics of the surface. The most pressing issue was the need to create a single seamless exterior for the external shell, a feat architect Norman Foster once believed to be nearly impossible.
While the sculpture was being constructed, public and media outlets nicknamed it "The Bean" because of its shape, a name that Kapoor described as "completely stupid". Months later, Kapoor officially named the piece Cloud Gate. Critical reviews describe the sculpture as a passage between realms. Three-quarters of the sculpture's external surface reflects the sky and the name refers to it acting as a type of gate that helps bridge the space between the sky and the viewer. In 2008, the sculpture and plaza were sometimes referred to jointly as "Cloud Gate on the AT&T Plaza". It is Kapoor's first public outdoor work in the United States, and is the work by which he is best known in the country according to the Financial Times.
Construction and maintenance
The British engineering firm Atelier One provided the sculpture's structural design. They started out with a wooden model, then transitioned into a digital image that was sent to multiple potential fabricators to make sample sheets of steel. These sample sheets of steel would help Kapoor choose who he would want to work with for the project. After seeking out three potential firms, Kapoor would end up choosing Performance Structures, Inc. Kapoor chose this team because they returned the highest quality sample and because of their ability to produce nearly invisible welds. Initially, PSI planned to build and assemble the sculpture in Oakland, California, and ship it to Chicago through the Panama Canal and St. Lawrence Seaway. However, this plan was discarded after park officials deemed it too risky, so the decision was made to transport the individual panels by truck and to assemble the structure on-site, a task undertaken by MTH Industries.The sculpture's weight raised concerns. Estimating the thickness of the steel needed to create the sculpture's desired aesthetics before fabrication was difficult. Cloud Gate was originally estimated to weigh when completed. However, the final figure was almost twice as heavy at. This extra weight required engineers to reconsider the sculpture's supporting structures. The roof of the restaurant Millennium Hall, formerly known as Park Grill, upon which Cloud Gate sits, had to be built strong enough to bear the weight. The large retaining wall separating Chicago's Metra train tracks from the North Grant Park garage supports much of the weight of the sculpture and forms the back side of the restaurant. This wall, along with the rest of the garage's foundation, required additional bracing before the piece was erected. Cloud Gate is further buttressed by lateral members underneath the plaza that are anchored to the sculpture's interior structure by tie rods.
Inside Cloud Gate
When Cloud Gate's interior components were completed, construction crews prepared to work on the outer shell; this comprises 168 stainless steel panels, each thick and weighing. They were fabricated using three-dimensional modeling software. Computers and robots were essential in the bending and shaping of the plates, which was performed by English wheel and a robotic scanning device. Metal stiffeners were welded to each panel's interior face to provide a small degree of rigidity. About a third of the plates, along with the entire interior structure, were fabricated in Oakland. The plates were polished to 98 percent of their final state and covered with protective white film before being sent to Chicago via trucks. Once in Chicago, the plates were welded together on-site, creating 2,442 linear feet of welded seams. Welders used keyhole welding machines rather than traditional welding guns. The plates were fabricated so precisely that no on-site cutting or filing was necessary when lifting and fitting them into position.
When construction of the shell began in June 2004, a large tent was erected around the piece to shield it from public view. Construction began with the omphalos, where plates were attached to the supporting internal steel structure, from the inside of the sculpture downward to the outermost surfaces. This sequence caused the structure to resemble a large sombrero when the bottom was complete.
The shell of Cloud Gate was fully erected for the grand opening of Millennium Park on July 15, 2004, although it was unpolished and thus unfinished, because its assembly had fallen behind schedule. The piece was temporarily uncovered on July 8 for the opening, although Kapoor was unhappy with this as it allowed the public to see the sculpture in an unfinished state. The original plan was to re-erect the tent around the sculpture for polishing on July 24, but public appreciation for the piece convinced park officials to leave it uncovered for several months. The tent was again erected in January 2005 as a 24-person crew from Ironworkers Local 63 polished the seams between each plate. In order to grind, sand and polish the seams, six levels of scaffolding were erected around the sides of the sculpture, while climbing ropes and harnesses were used to polish harder-to-reach areas. When the upper and side portions of the shell were completed, the tent was once again removed in August 2005. On October 3, the omphalos was closed off as workers polished the final section. Every weld on the Cloud Gate underwent a five-stage process, required to produce the sculpture's mirror-like finish.
| Stage | Name | Equipment used | Sandpaper type | Purpose |
| 1 | Rough cut | , 4½-inch electric grinder | 40-grit | Removed welded seams |
| 2 | Initial contour | ,, air-driven belt sander | 80-grit, 100-grit and 120-grit | Shaped the weld contours |
| 3 | Sculpting | air-driven, belt sander | 80-grit, 120-grit, 240-grit and 400-grit | Smoothed the weld contours |
| 4 | Refining | double action sander | 400-grit, 600-grit and 800-grit | Removed the fine scratches that were left from the sculpting stage |
| 5 | Polishing | electric buffing wheel | of rouge | Buffed and polished the surface to a mirror-like finish |
Cloud Gate was finally completed on August 28, 2005, and officially unveiled on May 15, 2006. The cost for the piece was first estimated at $6 million; this had escalated to $11.5 million by the time the park opened in 2004, with the final figure standing at $23 million in 2006. No public funds were involved; all funding came from donations from individuals and corporations.
Kapoor's contract states that the constructed piece should be expected to survive for 1,000 years. The lower of Cloud Gate is wiped down twice a day by hand, while the entire sculpture is cleaned twice a year with of liquid detergent. The daily cleanings use a Windex-like solution, while the semi-annual cleanings use Tide. A notable February 2009 incident saw two names etched in letters about tall on the northeast side of the curved sculpture. The graffiti was removed by the same firm that did the original polishing.
In August 2023, the City of Chicago began renovation and construction work on Grainger Plaza, which also closed public access to Cloud Gate. The work involved accessibility improvements, including ramps and new steps, replacing pavers, and waterproofing. After being behind fencing for most of a year, the sculpture was reopened to the public on June 23, 2024.