Pictures at an exhibition
I remember when I was in high school I bought the album 'Pictures at an Exhibition' - it was one of those life changing events for me. ELP was a bridge between the world of rock, (which I loved so much) and the world of classical music (that I played). Keith Emerson was known for slipping in a phrase or a few bars from a classical piece. 30 years later I am still surprised and amused when I hear an orchestra play a melody that i first heard Keith play on his Hammond organ. (check out this list of Keith Emerson Musical Quotes). 35 years after they first played Pictures, ELP is remembered as being pompous, bombastic - but I don't think you'll find too many performances that are as exciting as this.