Through two critical contributions, this text looks at the evolution and roles that have been assumed today by the facade envelope in contemporary architectonic output. The ever-more radical separation between structure and shell entrusts to the latter the expressive and communicative functions of the building. This appears to represent a belated victory for that bekleidung prinzip - which, though first expressed a century ago, opened the discussion on an articulated and problematic phenomenon, whose basis we can investigate today with technical knowhow and new theoretical knowledge. The evolutionary dynamics of the processes of planning and building in architecture, external factors related to the marketplace and the production of new materials filled with untapped expressive potential, the increase in the demand for results and performance of the building system, all these have had their influence on the phenomenon.