The article identifies and observes critically two emblematic cases of modern utopia of 1920s: Das rote Wien and Das neue Frankfurt. These two architectural experiences correspond to two alternative but complementary spatial and social models, the courtyard block (Hof) and the settlement (Siedlung). Through the historical distance today we can observe in critical way these experiences, analyzing the effects of utopian character within the contemporary city. Referring to the theoretical concepts of “utopia” and “realism” by Tafuri, the analysis tries to show the spatial elements that characterize these examples. The comparative approach highlights that today their solutions produce spatial quality at the urban and housing scale. In this way, Höfe and Siedlungen represent a “vision”. The actuality of utopia of social housing in Vienna and Frankfurt is the starting point to reflect to the contemporary architecture and collective living.