Question: What opera that Gerd Grochowski performed in was the last of four music dramas?
Sentence (from "Gerd Grochowski"): He appeared in leading roles as a guest artist at the Bayreuth Festival, the Berlin State Opera, the Bavarian State Opera, the Frankfurt Opera, the Hamburg State Opera, La Scala, the Liceu, the Linz State Theatre, the Stuttgart Opera, the Teatro Real, the Theater an der Wien, and the Salzburg Festival.
Relevant evidence: No