Although we had been unable to enter earlier in the day because a wedding ceremony was taking place (apparently a common occurrence), after our orchestral performance of Nabucco at the Grosses Festspielhaus, we happened to see people entering St. Peter's Abbey and upon entry discovered that we had come upon what turned out to be a wonderful (and free!) two hours choral performance of Mozart pieces. The acoustics and atmosphere were great, and the audience was invited to sing along for the last piece. (As an aside, we were quite impressed the large number of people who were able to sing along with a rather difficult Mozart piece and surmised that it was possibly due to the musical standards in Austrian schools being very high.)
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