Yves Klein was a leading member of the French post-war movement Nouveau réalisme, a pioneer of performance art, and is perhaps best known for the paint colour he patented in 1960, International Klein Blue (IKB), an ultramarine blue that he felt unlocked the endless void of space. Klein's iconic monochromes, initially executed in different colours, were first exhibited at the Club des Solitaires and Galerie Colette Allendy, both in Paris, in 1955 and 1956 respectively. In 1957, Klein held an exhibition at Galleria Apollinaire, Milan, in which he exhibited 11 identical blue canvases. Klein went on to hold performances in which naked female models acted as 'living brushes', as they rolled and were dragged across canvases; experimented with burning canvases and exposing canvases to rain while speeding in a car; created pigmented sculpture; and employed gold leaf and sponges in his work, amongst other radical conceptual and experimental practices. In his lifetime, Klein was given a retrospective at the Museum Haus Lange, Krefeld, Germany, and exhibited at the Leo Castelli Gallery, New York, and was commissioned to create a series of monumental murals at the Gelsenkirchen Opera House, Germany. His work is included in numerous international public collections, including the Philadelphia Museum of Art, Philadelphia; Museum of Modern Art, New York; Tate Modern, London; and Centres Pompidou, Paris.