Europe's two largest opera houses are in Paris (the Palais Garnier) and Vienna (the Wiener Staatsoper, or Vienna State Opera).
For reasons that I don't understand, Wikipedia refers to the Vienna State Opera (on its Teatro Massimo page) as the K. K. Hof–Opernhaus. This name is not mentioned on Wikipedia's Vienna State Opera page.
A search on DuckDuckGo, in an attempt to clarify, came up with no end of matches, but all were comparing it to the Teatro Massimo and all used exactly the same wording as Wikipedia. Funny, that. After the first twenty hits I gave up.
© Haydn Thompson 2020