Sonisphere is quickly becoming the biggest and most important festival of the summer.
Already exceeding fans' expectations, with line-up announcements such as the Big Four (Metallica, Slayer, Megadeth and Anthrax), Slipknot and Biffy Clyro, a new raft of impressive acts have been added to the swelling bill.
The Mars Volta, Opeth, Killing Joke, Four Year Strong, The Black Dahlia Murder, Black Tide, Watain, Firewind, Rise To Remain, Alestorm, Six Hour Sundown and The Treatment have all been confirmed to appear at the Knebworth based festival.
Previous announcements included Weezer, Limp Bizkit, Architects, Motorhead, Airbourne, Sisters of Mercy, Mastodon, Volbeat, Gallows, In Flames and Parkway Drive.
Sonisphere takes place July 8th-10th.