The event calender of Nuremberg is packed with unique and special events throught the year. Nuremberg’s musical life has much to offer, spanning the annual International Nuremberg Organ Week ION, Europe's largest and oldest festival for sacred music; to "Rock in the Park" and the world music festival Bardentreffen. The Bardentreffen, which is completely free of charge, takes place on a weekend and attracts over 200,000 music fans every year. The two summer concerts Classic Open Air presented by the Nuremberg Philharmonic and Symphony Orchestras lure more than 100,000 music fans to the Luitpold Grove for a picnic and classical music and are the biggest events of their kind in Europe. A sky blue lights glazes all over the city of Nuremberg its most important cultural event "The Night of Art and Culture" which enchants more than 140.000 visitors every year. Inspired by a special theme - the ancient squares and buildings of this historic city are thriving with life amongst light installations and all kinds of art performances.