Last year's Sonisphere festivals marked the first time thrash's Big Four -- Metallica, Slayer, Megadeth and Anthrax -- shared a stage, let alone toured together. On July 8, metal dreams are coming true again at the UK festival as the legendary acts round out an entire European Big Four tour there.

Also confirmed for Sonisphere, which takes place July 8-10 at Knebworth Park, are Slipknot.

Rumors are still circulating about whether a Big Four tour is going to happen in the States, and Megadeth frontman Dave Mustaine has been fanning the anticipation, hinting via Twitter. "Just went through a couple weeks of hell arranging something special for summer. Stay tuned! We're going to have some Big shows coming up."

Now if that means a US tour with Metallica, Slayer, Megadeth and Anthrax or just the overseas Sonisphere trek is anyone's guess.