Patrick Geddes, over a century ago, placed local identity at the basis of planning processes, or rather, “the personality of the place” as the foundation for defining future strategies. Over time, the process of morphogenesis of cities and territories has sedimented spatial configurations that have lost, on the one hand, the capacity to manage a dynamic equilibrium with the ecosystem of reference and, on the other, the capacity to activate emotions and feelings for the generation of a living well-being in a place. Over the course of the 20th century, the problem has been developed by various authors, with multiple theoretical apparatuses, taken up again to trace a path of comparison with the law for the spatial planning of the Tuscan Region. All the reasoning posed develops the assumptions for territorial planning around the concept of invariant, understood as a dynamic rule for the heritage reproduction of territories, or rather, as a rule for the management of ecological dynamics, capable of producing that topological identity, for the generation of a special local world, differentiated therefore from others, and therefore unique.