Commonly called the Bean for its distinctive kidney-bean shape and silver surfer polish, the Cloud Gate located in the Millennium Park is arguably the most famous landmark of the Windy City, Chicago. The gleaming gate made up of 168 stainless steel plates welded together, and its highly polished exterior reflecting the famous skyline of Chicago and the clouds above.
It gracefully curves in on itself, beckoning visitors to come to the concave chamber beneath the sculpture to touch its mirror-like surface and see their image reflected back a variety of perspectives. It was named Cloud Gate, as three quarters of its external surface reflects the sky, and the gate acts as a bridge between the sky above and the viewers below.
The 110-ton elliptical sculpture forged of a seamless series of highly polished stainless steel plates is the first public outdoor work of the British artist Anish Kapoor installed in the United States. The design of the gate was inspired by liquid mercury, and the visitors are free to walk around and under the 12 feet (3`7 m) high arch of the gleaming gate. The 66 feet long and 33 feet tall Cloud Gate was unveiled before its completion during the opening celebration of the Millennium Park in 2004. However, it was formally dedicated on 15 May 2006 and now serves as a famous symbol of the city and is one of Chicago’s most photographed attractions.
However, before the installation of the structure the authorities were concerned about certain practical problems. They were worried about the fact that as the structure was planned to be installed outdoors, it could retain and conduct too much heat to be touched during the summer and too cold during the winter. The extreme variation of temperature between seasons was also feared to weaken the structure. Bird droppings, fingerprints, and unwanted graffiti were also potential problems affecting the aesthetic beauty of the smooth outer surface.
To avoid producing unwanted indentations on the exterior shell, the supporting structural components were designed and constructed to ensure that no specific point was overloaded. Apart from that the frame was also designed to expand and contract with the sculpture with the fluctuation of temperatures. While the British engineering firm Atelier One provided the sculpture's structural design, Performance Structures, Inc. (PSI) was chosen to fabricate due to their special ability to produce nearly invisible welds.
Before the beginning of the construction of the shell in June 2004, a large tent was erected around the piece to shield it from public view. But the structure was temporarily uncovered on 8 July 2004 for the opening of the Millennium Park, much to the displeasure of the artist who disliked the public viewing of the monument in its unpolished and unfinished condition. Finally, after the erection of the tent again in January 2005, a band of 24 crews started to polish the seams between each plate, and the shield of the tent was permanently removed in August 2005, after the completion of the upper and side portions of the shell.
Currently, the Cloud Gate is manually wiped down twice a day, and around 40 us gallons of liquid detergent is used to clean the entire sculpture twice a year. In February 2009, two names etched in letters about one inch (25 mm) tall was found on the northeast side of the curved sculpture which was duly removed.