Chad has spotted a discussion topic that seems ripe for possibility in many fields. It started as a time traveler picking the coolest engineering projects of the 20th century to be involved with, no altering of history allowed. Chad altered the topic to scientific discoveries of the 20th century, though one commenter has broken this rule by invoking Archimedes. So I pose the question this way: what musical performance of the 20th century would you most want to either witness or take part in? Imagine performing in the orchestra for the Rite of Spring premiere in 1913, or being in the crowd at Stalag VIII in 1945 for Messiaen's performance of his Quartet for the End of Time? (Of course, that would mean you were either a Nazi or a POW, so quickly jump in and jump out for that one.) I think one of my wishes would be the Geneva International Music Competition in 1955 when Maurice Andre won and started his international solo career. Or to hear him premiere the Tomasi or Chaynes concerti composed for him.
Start dreaming of your own time travels!