The youngest of the three Castiglioni brothers, Achille, also studied architecture at Milan Polytechnic, taking his diploma in 1944, the year he joined the practice run by his two elder brothers, Livio and Pier Giacomo. Livio left the practice in 1952. The collaboration between Pier Giacomo and Achille Castiglioni was extremely productive for many years. The two younger Castiglionis made an ideal team, developing many designs together. In 1957 the exhibition "Colori e forme nella casa d'oggi" was mounted at the Villa Olmo in Como. There Pier Giacomo and Achille Castiglioni first presented their readymade designs: "Mezzadro", a stool consisting of a tractor seat mounted on a substructure, and "Sella", a stool featuring a bicycle seat to sit on while telephoning (both chairs produced years later by Zanotta. Pier Giacomo and Achille Castiglioni were particularly successful with the lamps they designed for Arredoluce, Artemide, and especially Flos. Founded in 1962, Flos produced the following lamps designed by Pier Giacomo and Achille Castiglioni: "Taraxacum" (1960), "Splügen Bräu" (1961), and "Arco" (1962), followed by many others. After the death of Pier Giacomo in 1968, Achille Castiglioni ran the practice alone. Achille Castiglioni exerted a crucial influence on 20th-century design with his functional yet beautiful designs. In 1971 Achille Castiglioni designed "Lampadina", a table lamp, in 1972 "Noce", and, in 1978, the hanging lamp "Frisbi", which, as its name implies, looks like a glowing Ufo. One of Achille Castiglioni's best known lamps is "Gibigiana", a table lamp dating from 1980. In 1998 Achille Castiglioni designed "Diabolo", a hanging lamp, for which he was again awarded the Compasso d'Oro, at the age of eighty. Achille Castiglioni's designs are notable for the playful way in which defamiliarization and a striving for minimal form are united. Function ranks above aesthetics yet Achille Castiglioni always believed that a good designer object had to be both functional and beautiful. Achille Castiglioni's philosophy of design is summed up in the following statement he once made: "So sophisticated and so simple – I like that!". Achille Castiglioni was a professor of industrial design at Turin Polytechnic between 1970 and 1980. From 1982 until 1986 he taught spatial design and industrial design at Milan Polytechnic. Numerous works by Pier Giacomo und Achille Castiglioni are in the collection owned by the Museum of Modern Art in New York.