This thesis explores the agency of the colonnade as third space to balance the relationship between work and the urban public environment. Typical strategies to deliver such collaborative and social space rely on either the hyper-flexibility of a free plan or the specificity of program. In contrast, this thesis projects a third position using formal specificity within the colonnade to exploit the spatial ambiguity of a threshold. By putting third space functions in the colonnade threshold around the office, contemporary work shifts to an urban-oriented model of public collaboration. This opens production to the city and allows for unpredictable interactions that could benefit both parties.