Pianist Henrik Kilhamn goes into the details of Keith Jarrett's legendary improvised concert in Köln 1975. In the substantial "A section" the music is centralized around the two chords Am and G. Jarrett goes between them in an almost hypnotic state through several different styles. After that he embarks on a free exploration in the "B section" before finding the way back to A major in the final "C section".
Link to Youube video: https://youtu.be/8GkqrlKkKFA