Metallica - Metallica Close 'The Big 4'

Metallica wowed fans this weekend with a historic uniting of the most significant bands in heavy metal.

Metallica took the main headline slot at the 'Big 4' festival, which was held at the Empire Polo Club in Indio, California.

The one-day festival, which took place on the same site as the Coachella festival had graced a week previously, saw over 50,000 fans flock to see 4 legendary heavy metal acts, affectionately dubbed 'The Big 4': Metallica, Anthrax, Slayer and MEGADETH.

Fans flocked from all over America to see the event, including some from as far as Ontario, Canada, Press Enterprise reports: "The passion of the fans burst through the night with sing-a-longs that even topped Metallica's incredible volume on songs like "Sad But True," "Master of Puppets" and "Welcome Home (Sanitarium)."

According to Press Enterprise Metallica were more than grateful for the privilege: "After finishing "Fuel," singer James Hetfield got serious with the crowd about the show.

"This is history tonight and I'm glad you are a part of it. Thank you for showing up," he said.

This was the only US date for this line-up, which will also appear at European festival Sonisphere (Knebworth, UK) in July 2011.