The Gereonsklub was an avant-garde artists' association in Cologne in the years immediately prior to World War I.
Named for the Gereonshaus building designed by the architect Carl Moritz, in which Oppenheimer had a studio, it opened in January 1911 and closed in 1913.
[1] The Gereonsklub operated as a center for lectures and exhibitions and had a painting school run by Oppenheimer.
[1] Emmy Worringer and her brother Wilhelm, an art historian, booked the lectures and organized the exhibitions.
[1][5][6] In its short history, it exhibited such notable artists as Franz Marc (1911), Paul Klee (1912), Robert Delaunay (1913), and August Macke.