We propose to revisit Patrick Geddes’s work from 1914-1924 in India in order to rethink ideas about how redesign cities of today. In doing so, we will focus on the city of Valencia, Spain. Water has long played a fundamental role in its composition and evolution. Vegetation has recently made a striking reappearance there inside abandoned downtown urban wastelands, transforming them into a living network. Considering these areas, we will argue that at approach in terms of what the natural history of the urban space can help to rethink the relation between urban and natural ambiances. The starting-point for this exploratory approach is the study of this particular urban territory as it developed historically within the city; as it has appeared over time. This amounts to reconstructing existing historical narratives of the city’s growth to include hydrological factors, referenced back to their pre-anthropic origins. The approach is here called ‘natural memory’. A second aspect of our method, concerning what could be termed the ‘urban stratigraphy’, will consist in researching the pre-material and intangible layers that compose the urban palimpsest. We will associate these two aspects with a third, more explicitly design-oriented one; the prospect of a ‘reactivation’ of the city hydrological substratum in association with several recent collective projects and experiences that have recently been taking place in Valencia’s downtown urban voids. This mode of reinterpretation of the urban palimpsest constructs a framework and a narrative for a new understanding (or rereading) of the territory seen the point of view of its ambiances, suggesting new possibilities for the future of these spaces. In light of the current tendency of quarter’s re-qualification by the activation of diverse local micro-initiatives, relating particularly to natural elements, and singular uses of common spaces, Geddes’ work appears surprisingly pertinent and useful for rethinking contemporary urban condition in general and research on ambiances in particular.