This paper presents an empirical study focusing on the role of mock-ups to support user/citizens co-creation and the anticipation of the User eXperience within a specific urban Living Lab. Scholars have previously identified different principles characterizing a Living Lab, such as: " realism " , spontaneity, continuity and empowerment, which represent the " live " dimension of Living Labs. However, these principles are quite difficult to practically implement. Nonetheless, we conducted an experiment in the context of an urban project dedicated to the design of mobility stations that reveals the paramount importance of the mock-up role for implementing the " realism " principle. The findings unveil the great potential of close-to-real-life immersion of users/citizens in realistic environments to not only fulfilling the " realism " principle but also greatly contributing to the adoption by users/citizens. Finally, this study gives some elements to support citizens' engagement in the co-creation stage of the urban design process towards the realization of smart-cities.