From the opening salvo of his mammoth exhibition “Le Musée qui n’existait pas” at the Centre Georges Pompidou—a giant square of red-and-white-striped canvas hung in the entry forum—one had the feeling that, unlike the Museum that hadn’t existed, this is the Daniel Buren that always was. Not only were the artist’s signature stripes everywhere to be seen, reflected by a seeming infinity of mirrors on walls and ceilings, but the “cabane éclatée” (exploded shack), Buren’s anti-architectural ploy, was the material support for the parodic museum. A labyrinthine network of shantylike cubicles, all