Carrara marble base, stainless steel stem, steel reflector. With Pier Giacomo Castiglioni. A street light inspired the iconic "Arco", which is a ceiling light that sits on the floor on an extremely heavy marble base. The hole in the base is to insert a broomstick for carrying. About the base, Castiglioni said: "Our first idea was concrete, but we chose marble because it gave us the same weight in a smaller volume and a better finish for a lower cost. Nothing in Arco is decorative. Even the bevelled corners of the base are functional, they avoid sharp angles, which could be dangerous."