This book explores the relationships, intersections and collaborations between art and architecture through the "Kunst am Bau" (art in architecture) and the national exhibition pavilions in art biennials. "Art in architecture" and pavilions represent hybrid situations where both artists and architects are co-authors in the making of space. Although the communication between them is sometimes a source of conflict, resulting in conventional or merely contractual practices, they share a common ground. What is their specificity, today ? The book brings into question the multiple roles played by pavilions and "Kunst am Bau" between artistic and architectural interventions, public policies and the exhibition of art and architecture.