High Quality Content by WIKIPEDIA articles! The Opening Ceremony of the 2004 Summer Olympic Games was held on August 13, 2004 at the Olympic Stadium in Maroussi, Greece, a suburb of Athens. 72,000 spectators attended the event, with approximately 15,000 athletes from 202 countries participating in the ceremony as well. It marked the first-ever international broadcast of high definition television, undertaken by NBC and the Japanese television station NHK.