This is the opera house even in the new TBC instance Karazhan. This shows the Wizard of Oz fight, which is just one of the three battles you can get, the others being Little Red Ridinghood and Romeo and Juliette.

Music:
Godspeed You Black Emperor! - Storm
Disney - Ding Dong! The Witch is Dead

I included basic strategy on how to beat the event for those who wonder.

I used AG Unit Frames for BC incase anyone was wondering..