is a 53-foot (16 m) tall, 50 ton stabile, by Alexander Calder, located in the Federal Plaza in front of the Kluczynski Federal Building in Chicago, Illinois. It was commissioned by the United States General Services Administration and was unveiled in 1974.
It is composed of steel, and is vermilion in color, to offset it from the black and steel surroundings of nearby office buildings. The stabile is an art form which Calder pioneered. It is an abstract structure that is completely stationary, as opposed to a mobile, which can move with air currents. Despite the large size of the sculpture, its design is such that viewers can walk underneath and around it, thus enabling one to perceive it in human scale.