The Italian designer and Architect Pier Giacomo Castiglioni is the second of the three famous Castiglioni brothers. Like his brothers, Pier Giacomo Castiglioni studied Architecture at Milan Polytechnic, taking his degree in 1937. In 1938 Pier Giacomo Castiglioni and his older brother, Livio Castiglioni, founded an Architectural practice in Milan, which the youngest brother, Achille Castiglioni, joined in 1944.
Until his untimely death in 1968, Pier Giacomo Castiglioni collaborated with Achille Castiglioni on numerous design projects. The two brothers were particularly successful with lighting designed for Arredoluce, Flos, and Artemide. They playfully explored new possibilities for form, linking technical innovation and Minimalist economy of means to produce highly functional objects which were just as aesthetically satisfying as they were practical. In 1955 the Castiglionis designed Luminator for Arredoluce, and later Taraxacum and Splügen Bräu for Flos. Perhaps most famously, the Castiglioni design Arco for Flos in 1962 remains a classic to this day.