What makes a city meaningful to its residents? What attracts people to live in a city and to care for it? Today, we might see such questions as concerns for HCI, given the emerging agendas of smart and connected cities, IoT, and ubiquitous computing: city residents’ perceptions of and attitudes towards smart city technologies will play a role in technology acceptance. Theories of “placemaking” from humanist geography and urban planning address themselves to such concerns, and they have been taken up in HCI and urban informatics research. This theory ofers ideas for developing community attachment, heightening the legibility of the city, and intensifying lived experiences in the city. We add to this body of research with an analysis of several initiatives of City Yeast, a community-based design collective in Taiwan that proposes the metaphor of fermentation as an approach to placemaking. We unpack how this approach shapes their design practice and link its implications to urban informatics research in HCI. We suggest that smart cities can also be pursued by leveraging the knowledge of city residents and helping to facilitate their participation in acts of perceiving, envisioning, and improving their local communities, including but not limited to smart and connected technologies.