WIKIPEDIA:

“ The Big 4 Live from Sofia, Bulgaria is a DVD/Blu-ray featuring live concert performances by Metallica, Slayer, Megadeth, and Anthrax, collectively known as "the big four" of thrash metal. The event took place on June 22, 2010 at the Sonisphere Festival at Vasil Levski National Stadium, Sofia, Bulgaria. Before its DVD release, it was shown at 450 movie theaters in the United States and over 350 movie theaters across Europe, Canada, and Latin America on June 22, 2010.
Critical reviews of the DVD were mostly favorable. Websites such as Allmusic and About.com were positive, though Blogcritics gave the DVD a mixed review. The DVD peaked at number one on the United States, United Kingdom, Austrian, and Canadian charts, and also charted on three other charts. It was certified gold in Germany, and provided Slayer with its first platinum certification.

Background and release
On Wednesday, June 16, 2010 at the Sonisphere Festival at Bemowo Airport in Warsaw, Poland, the "big four"—Metallica, Slayer, Megadeth, and Anthrax performed together for the first time. The members of the four bands (except for Slayer's Jeff Hanneman) were first photographed together on the previous day. Their live concert, on June 22, was for one night only. [......] ”

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