Louvre-Lens, a luminous outpost of the venerable Paris museum, opened in mid-December in the northern French town of Lens. The architect SANAA teamed up with Imrey Culbert and then Adrien Gardère for exhibition design, and with Catherine Mosbach for landscape. The result is a series of evanescent, one-story glass-and-aluminum pavilions delicately displaying masterpieces of art.