On April 25, Gagosian will open its new Upper East Side outpost. This is welcome news, considering the closure of the gallery’s long-standing space at 980 Madison Avenue last year. The inaugural exhibition centers on works by Marcel Duchamp, but a smaller show features six early pieces by Robert Rauschenberg from the Cy Twombly Foundation—a pairing that pays tribute to the two artists’ long friendship. Rauschenberg and Twombly met in 1951 at the Art Students League of New York, went on to attend the storied Black Mountain College, in North Carolina, and traveled together through their formative professional years. Their closeness left unmistakable traces on each other’s work, as we now see with Rauschenberg’s very first sculptures, made in 1950 and preserved by Twombly. Other early pieces, including a photogram made by Rauschenberg and Susan Weill before they were married, are also on view. —Jeanne Malle