Complex sentence: The Donaueschingen Festival for contemporary music ("Donaueschinger Musiktage"), founded in 1921 and one of the world's oldest festivals for new music, takes place every year in October.
Split into simpler sentences: The Donaueschingen Festival for contemporary music ("Donaueschinger Musiktage"). Founded in 1921, one of the world's oldest festivals for New music takes place every year in October.