In Villeneuve d'Ascq, the emphasis is on the artist's beginning through the refinement of his "visua1 tool" (striped canvas in bands 8.7 centimeters wide, alternately white and color) in 1967 Also on offer, in Villeurbanne, is a retrospective of the "Cabanes," an in-progress suite begun in 1982 that takes architecture and the notion of in situ (central to Buren's thought) in a radically new direction.