Imagine the gasps from passers-by when brothers Achille and Pier Giacomo Castiglioni revealed their new Arco lamp in the windows of a Milanese department store, La Rinascente, in 1962. Was it a floor lamp? Was it a pendant light? Was it a reading lamp? The Arco’s sweeping curve challenged old ways of lighting a room and would become a symbol of the swinging ’60s.