In the main hall of Union Station, where train travelers wait for the next departure, headphones are a common sight. Opera singers in the middle of a performance, however, are less common. "Invisible Cities," a new opera by Christopher Cerrone, combines all three. Attendees will wander through Union Station wearing wireless headphones as they listen to a live performance of the opera, in which Kublai Khan and Marco Polo ponder the existence of cities and imagination, happening in the same space. The Industry, an experimental opera company, is collaborating with the L.A. Dance Project, headed by choreographer and dancer Benjamin Millepied.