Abstract. With the prevalent ubiquitous computing technologies, it is possible to explore novel solutions for supporting civic engagement as a set of urban practices. One interesting urban practice is the soapbox, traditionally conceived as wooden structure, from where to hold impromptu speeches. For this thesis, a novel soapbox prototype with ubiquitous computing mediated technologies is introduced, with our focus on the feasibility and performance analysis of its middleware support, investigating how our middleware is able to meet the goals of a situated virtual-physical civic engagement platform. Based on our empirical evaluations, it is demonstrated that our prototype is effective to support civic engagement and serve purpose of continuously soapbox streaming