Plane surfaces predominate in this factory. The glass and iron walls are joined cleanly at the corners without the intervention of piers[…]. [Peter] Behrens bounded the glass walls of his famous Turbine Hall right and left with monumental cyclopean walls. These have disappeared with [Walter] Gropius. His walls show that they are no longer supporters of the building, but simple curtains, protection against inclement weather, as Gropius put it.