Watch VoirFilms. When the 'Big Four' - Metallica, Slayer, Megadeth and Anthrax - shared a stage together on 22nd June 2010 in Sofia, Bulgaria, the show was beamed live into over 550 theatres worldwide via satellite in a special HD cinematic event. The legendary concert from the Sonisphere Festival was one of only 7 shows across Europe when the four monsters of metal shared a stage for the first time.