Answer
Tarja Turunen has performed at many music festivals, including Graspop Metal Meeting and Wacken Open Air. Graspop Metal Meeting is an annual metal festival that takes place in Dessel, Belgium. It is one of the largest metal festivals in the world, and has featured acts such as Metallica, Iron Maiden, and Slayer. Wacken Open Air is another annual metal festival that takes place in Wacken, Germany.