Rethinking architectural thresholds through urban circulation. The utopian present of theory and practice in Alison and Peter Smithson’s ‘Streets-in-the-Sky’

The paper aims at underlining the further developments of the approach of ‘streets-in-the-sky’ both as a theoretical framework with the Golden Lane Competition Entry, and as a design practice, with the mirror of the Robin Hood Gardens Housing Complex – in their role as practitioners in producing architectural culture related to the relationship between the architecture and urban languages. Was the meaning of such a theoretical model conveyed through the physical representation? Was this a Deductive or Inductive process? A peculiar role in this framework is given to the dimension of environmental performance, presented in the character of the building envelope as a membrane, in the evolution of the concept of threshold as a matter of comfort.