Please answer the following question: The House of Atreus Act I released in 1999 is the ninth studio album by the American heavy metal band Virgin Steele. It has the subtitle A Barbaric-Romantic Opera. This album is the first part of a metal opera inspired by the Oresteia a trilogy of Greek tragedies written by Aeschylus which concerns the end of the curse on the House of Atreus. The music was intended to be the soundtrack for theatrical shows with actors impersonating the characters of the tragedy. Given a list of categories: company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work, what category does the paragraph belong to?
A:
Album