Detailed Instructions: In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.
Q: Passage: In 1944, she returned to Switzerland, singing as the leading dramatic contralto at the Opernhaus Zurich. She appeared as Brangane in Wagner's Tristan und Isolde, as Fricka in his Die Walkure, as Ortrud in his Lohengrin, and in the title role (Octavian) of Der Rosenkavalier by Richard Strauss, among others. In 1949, she took part in the premiere of Willy Burkhard's Die schwarze Spinne. The same year, she performed in Monteverdi's L'incoronazione di Poppea, both at Vicenza's Teatro Olimpico and at La Fenice in Venice. She performed as a guest at La Scala in Milan several times, including Octavian, Brangane, Venus in Wagner's Tannhauser, and the title role of Honegger's Judith. She appeared as a guest at the Vienna State Opera, in Belgium, France, United Kingdom, in Argentina, and the US.
Link Information: The first permanent theatre, the , was built in 1834 Question: When did the opera house where Elsa Cavelti sang leading dramatic contralto in 1944 open?
A:
Answer: 1834