This chapter explores a conceptual framework based on archaeological thinking, to provide a conceptual toolbox for how a temporal past can be enabled in the context of urban planning. It discusses various ways in which concepts about temporality and the long-term duration of time, evident in urban archaeological layers and a fragmented past, can be defined as heritage values. The chapter argues that the concept of ‘deep cities’ is a valuable resource in urban planning and sustainable urban development projects; and the long-term duration of time takes account of the needs for change and for new cultural imprints in the city without neglecting its deep historical continuity. It examines theoretical reflections on archaeology as a conceptual resource for defining urban heritage values. The chapter describes a theoretical approach based on heterotopia as a methodological resource, using six principles to characterise heterotopic places and distinguishing four heterotopic features of urban heritage values: dissolution, collage, palimpsest and stratigraphy.