The new century began with an economic crisis and environmental and health catastrophes, and is projecting us into a new complex dimension of our living in which we are witnessing a fundamental paradigm shift, not only in our understanding of the present, but of the future in particular. We can no longer use methods and systems belonging to the scientific and reductionist paradigm of the recent past, because we are currently in a new and different condition, in an ongoing search for ethical and social relations. The scientific paradigm in which everything was decomposed and then reorganized according to a universal principle of knowledge, or the reduction of complexity into simplicity, is currently no longer applicable to knowledge in general, to living the Earth, and even less so to architecture. The disjunctive logic of Cartesian analytical theory, which distinguishes and separates and decontextualizes, used by such masters of the past century as Le Corbusier, Mies van der Rohe, and Aldo Rossi, becomes insufficient. Instead, it is necessary to differentiate and connect, to conceive the project as something that is not exhausted in the juxtaposition or the sum of the parts, but rather as a system full of links, interactions, relationships, transversality, variability, mutation, and adaptation. In the age of complexity, we must therefore refer to a new approach, based on architectural and social activism, one that is ecosystemic, processual, hybrid, and inclusive. This book is a collection of six writings and projects describing the visions of possible worlds that prefigure a different approach than in the past, in which architecture, while operating on the existing that has been discarded, is asked to use new adaptive tools that, as a catalytic agent, can trigger chain reactions within the project of mutation, and activate a process of re-signification favoring a "syntagmatic overwriting" of a new social and architectural identity. Tools that in their overall constitutive identity constantly contribute to the change and co-production of the conditions of complex reciprocity with the existing, defining an approach that places architecture in an evolutionary dimension.