Question: The House of Atreus Act I, released in 1999 is the first part of a metal opera inspired by the  only extant example of an ancient Greek theatre trilogy which won first prize at what festival?
{'answer': 'the Dionysia festival', 'supporting_facts': [['The House of Atreus Act I', 0], ['The House of Atreus Act I', 2], ['Oresteia', 0], ['Oresteia', 2]]}