 One of his most famous works, "The Art of Riding in the Picture" is especially renowned among riders.He was also a member of the so-called "Siebener Club", an art association mainly composed of architects (including Josef Hoffmann, Joseph Maria Olbrich and Joseph Urban).In the 1920s Koch was invited to the United States by the U. S. Polo Association, members of which had heard him spoken of abroad as "the finest painter of horses in the world," to come to the U. S. and make pictures of the International Polo matches.