A solid and consistent research production has, up to now, considerably contributed to the identification and exploration of the meanings, theoretical foundations, and possible implications of tourism in the cities. The focus on pursuing sustainable tourism activities has also inspired different approaches (eco-tourism, responsible tourism, pro-poor tourism, among others). Nevertheless, difficulties still exist in the definition of concrete solutions to the complex problem of how to activate and facilitate the diffusion of sustainable urban tourism practices. Given the central role of indicators in the monitoring of transformation and defining impact mitigation measures, this article proposes an unexplored interpretation of such tools, which are specific for the built environment as a main component of the urban context. Starting from a broad examination of the literature on urban tourism and its related impacts, and focusing on heritage destinations, the authors highlight the potential of the built environment to play an active role in reducing the extent of potential flow impacts upstream of their actual occurrence. As a result, possible building-scale indicators that could integrate current downstream evaluation and mitigation practices are identified and suggested, and their possible implications are discussed alongside those of existing indicators. Finally, further developments for future research are suggested.