The interplay between built and empty space fascinates Dominique Perrault. To him, architecture invariably means, among other things, the embracing of the absence of structures. And so, for his Bibliotheque nationale de France the placement of the four large towers is of primary importance. They delineate a gigantic volume filled with nothing but air and sky. In an urban landscape which today grants little excess space to man, Perrault wants to use his architecture as a means of winning back quality of life. It appears to virtually sink into the ground, submerged in a treescape. Perrault's interests, understandably, tend towards urbanistic tasks.