Alfred Stieglitz's gallery at 291 Fifth Avenue was called 291.
The gallery took its name from its Manhattan street address, 291 Fifth Avenue. Stieglitz ran the space from 1905 to 1917, using it to show photography and modern European and American art. It became one of the most influential small galleries in early twentieth-century New York.
291 helped introduce American audiences to artists including Pablo Picasso, Henri Matisse, and Constantin Brâncuși. It also presented the work of photographers connected with Stieglitz's Photo-Secession movement.
Georgia O'Keeffe's first publicly exhibited works appeared there in 1916. After 291 closed, Stieglitz operated other New York galleries, including the Intimate Gallery and An American Place. Those later spaces should not be substituted for the address-based name 291.