In current debate about smart cities it is implied that "smartness" is something that needs to be added to cities. However, recent developments in urban modelling and cognitive science instead put forward the perception of the built fabric of cities as an extension of the human cognitive apparatus, which is why the physical form of cities is seen as embodied knowledge that is activated by human use. By extension, it is argued that the built form of cities also embodies social, cultural- and economical relations by structuring human daily routines. In this perspective, the built fabric of cities can be understood as highly intelligent artefacts rather than simple dead matter. New knowledge of this paves the way for developing the "smartness" of the city as built matter but also the efficacy of applied smart city systems.