Alfred Stieglitz's New York gallery was called 291.
The gallery took its name from its address at 291 Fifth Avenue in Manhattan. Stieglitz first opened it in 1905 as the Little Galleries of the Photo-Secession, and it became known simply as 291 after moving into the building's upper-floor rooms.
291 introduced American audiences to European modernists including Pablo Picasso, Henri Matisse, and Constantin Brâncuși, while also presenting innovative American artists and photographers. Stieglitz showed O'Keeffe's work there after receiving her early abstract drawings in 1916.
The gallery closed in 1917, but its influence was considerable. Its name is sometimes confused with Stieglitz's later galleries, especially the Intimate Gallery and An American Place. Those were separate spaces from the gallery known as 291.