Urban landscapes are characterized by the presence of artefacts, buildings and other constructions in the process of “becoming.” This chapter looks at the ways in which (un)sustainability is produced through signifiers of the “unfinished” in the physical environment, drawing on examples from urban areas in Sweden and South Africa. Inspired by semiotic landscapes studies and utilizing a social semiotics methodology, the chapter locates sustainability at the intersection of material and semiotic design and social practice. It identifies the ways in which the unfinished can signify the end of a cycle, pointing to unsustainable destruction or indexing a circular movement of sustainable reuse and repurposing in urban spaces. It shows how signifiers of the unfinished point to poor planning (in the case of unfinished highways) or non-inclusive urban developments (in the case of building sites). The chapter first looks at unanticipated abandonment (in the form of freeways), then at ways of designing for change in landscape architecture, and finally the ways that social practices can “defrost” unfinished structures that have become frozen in time. Here non-anticipated practices can initiate cycles of change even in cases where the original design was unidirectional. Through this study, the authors thus expand on the concept of “sustainability” and emphasize the multimodal and contextualized nature of sustainability discourses.