That was then...

Scott @ Musical Perceptions has an interesting meme: what musical performance of the 20th century would you most want to either witness or take part in? I've always had a time travel fantasy of hearing the great composer/pianists play, just wondering what they really sounded like, but since Scott specifies 20th century, I can't go back and hear Chopin or Liszt. Fortunately, for the imaginary traveler if not the real one, there are a number of legendary 20th century performances whose records, for as much as I like them, are a bad snapshot of the original concerts.

Two spatialization events spring to mind, never to be duplicated in a recording.

• The original staging of Xenakis' Persepolis in the ruins of the palace of Darius, at night, played over a hundred loudspeakers spread through the ruins, with fireworks, choreographed torch runners, natural fire, and huge projectors.  Kinda sticky politically, but still.   
• Actually, there were several Stockhausen events to make me yearn for time transport.  He played a series of concerts in the caves of Jeita, Lebanon, where he placed 180 speakers among the rocks and played his electronic and intuitive music in the inner dome of the caverns.  Or, the performance of Sternklang, with five groups of musicians spread around a park, sometimes taking musical material from one group to another with torch-lit runners. Gentle Fire, the new music/improv ensemble with Hugh Davies, was one of the groups.  Or the Expo 1970 world's fair in Osaka, where Stockhausen performed daily for a period of months in a special auditorium designed to his specs.