Today is the 100th anniversary of the opening of the world’s first dedicated art-photography gallery, Alfred Stieglitz’s “Little Galleries” of the Photo-Secession on an upper-floor at 291 Fifth Avenue, New York. The launch event was a little later, on the 25th November 1905. The “Little Galleries” later became his famous “291” Gallery, and – along the way – a vital hub in the social networking of American modernism.