Alfred Stieglitz ran the New York gallery known as 291 when he exhibited Georgia O'Keeffe's work.
The gallery was officially called the Little Galleries of the Photo-Secession, but it became widely known as 291 after its address at 291 Fifth Avenue in Manhattan. Stieglitz opened it in 1905, and it became an important venue for modern art and photography.
O'Keeffe's work was shown at 291 in 1916, after Anita Pollitzer brought Stieglitz photographs of her charcoal drawings. The exhibition helped launch O'Keeffe's professional relationship with Stieglitz and introduced her abstractions to the New York art world.
The gallery closed in 1917. Stieglitz later operated the Intimate Gallery and An American Place, so those names are connected to O'Keeffe but do not identify the earlier space. The number 291 refers to the address that gave the gallery its familiar name.