Robert Müller was a pioneer of iron sculpture. Departing from the traditional exploration of the figure, Müller worked in increasingly abstract styles as his career evolved, eventually progressing towards multi-piece metal assemblages. Beginning with meticulous draughtsmanship and painted studies, he often formed pieces separately before assembling them into unnervingly surreal objects and biomorphic forms. After the 1960s, Müller ceased using iron as his primary material and began applying his principles of construction to a variety of materials, including iron, brass, bronze, and marble.