Sigfrid Karg-Elert composed his Choral Improvisations for Organ, Op. 65, between 1906 and 1908. They were first published in 1909, dedicated to organist Alexandre Guilmant. Op. 65 consists in 66 pieces for solo organ (the last one with optional 2 trumpets in B♭, 2 trombones, and timpani). The pieces are grouped into six books.
