While perhaps most famous for placing a urinal in an art gallery, Marcel Duchamp was one of the most influential artists of the modern era. Philadelphia Museum of Art, the Association Marcel Duchamp, and the Centre Pompidou have launched the Duchamp Research Portal, an archive of more than 18,000 documents and 50,000 images dedicated to the artist. Daniel Cassady writes: “The most interesting items are often the most intimate and involve other major players in the evolution of 20th-century art: A 1950 letter—with enigmatic marginalia—from Breton. A 1933 postcard to Constantin Brancusi. Many candid photographs by Duchamp’s friend and fellow giant of the era, Man Ray.”