Hey there metal-heads! Well, punk, rock and metal-heads! I present you Rock am Ring! Isn't that a hell of a festival?! Rock am Ring (Rock at the Ring would be the translation) and Rock im Park (Rock in the Park obviously) are two simultaneous music festivals held in Germany.
Both festivals usually have the same lineups so they are regarded as same festival. Rock am Ring takes place in Nürburgring racetrack in the west of Germany, and Rock im Park is held around the Frankenstadion in Nuremberg, in the south of Germany.
The first Rock am Ring (1985.) was originally a one time festival, but due to commercial success it grew into annual one. Rock im Park was first held in Vienna in 1993, then moved its location a few times until it finally settled in Nuremberg. Together they are the largest music festivals in Germany and one of the largest in the world with a combined attendance of just over 150,000 people in 2007!!!
Fun fact from Wikipedia: "The 2007 festival was used in a science experiment to test the effects of large bodies of people simultaneously jumping. The experiment data was used to calculate the result if the entire Chinese population were to jump in unison. The experiment concluded no significant results would come from the theoretical event."
All additional info as well as line up for this year you can find here.