John, Charles de Gaulle airport is definitely the closest to Le Zenith. In fact, Le Zenith is in the north eastern corner of Paris, right on the way to Charles de Gaulle by taxi, and not far by the metro (change in Gare du Nord). See
http://www.parisdigest.com/transport/charlesdegaulle.htm for more information on Charles de Gaulle. Enjoy the show at Le Zenith.