This article examines the reciprocity between the web and the urban public domain, both considered as public space(s) or parts of the public sphere. Invisible Performances, a series of furtive actions performed in different sites of the city by Montreal-based artist Steve Giasson, documented through images appearing and circulating on the web, is analyzed following this perspective. The scheme (dispositif) imagined by Giasson is at the same time critical, playful and meant to creating communities. This artwork demonstrates the importance of the interactions taking place at the junction of urban sites and a sociotechnical environment, activated in resonance and in extension of each other.