From Hentschel
/* Opera house and St. Stephen's Basilica */
==== Opera house and St. Stephen's Basilica ====
The opera house is within walking distance from your hotel, one M1 subway/metro station down towards the river from the '''Oktogon'''square near your hotel. The '''Oktogon''' station is about 4 blocks or so from your hotel, you'll leave your hotel to the right.
If possible, try to get tickets to the Opera house for one night that you're there. It's the best sounding opera house in Europe after the Scala in Milan. If the place looks familiar, it's probably because you've seen it in a dozen or so hollywood movies as a movie location. If you get tickets (they tend to be reasonable), make sure to dress up :)