With its masterful form, architecture, material and use of space, Untitled, 1948 is a remarkable embodiment of Alexander Calder’s unparalleled contributions to the development of 20th century art. Calder undertook the mobile at an especially pivotal period in his career; the Second World War had just come to an end and government rations on steel, Calder’s material of choice, were finally lifted. In Untitled, we witness the artist working with a newfound appreciation for his favorite material, choosing to show the steel in its pure form. Today, the work comes to Sotheby’s from the esteemed collection of American fashion designer, entrepreneur and philanthropist Kay Unger.