Sustainable development represents a shared aspiration, the priority of which is widely recognised worldwide by scientists, decision-makers and public opinion alike. It became a topic for reflection and an endeavour for initiatives taken by local communities, businesses, regions, states and international organisations. The subject of sustainability is interdisciplinary and involves a complex thinking that recently led to the emergence of a new discipline, namely sustainability science. The systems approach (systemics) is deemed to offer a set of concepts and methods that enable the elaboration of visions, as well as the steering of the process of sustainable development in real contexts. Within this framework, the main strength of this approach consists in its capacity to overcome the reductionism peculiar to conventional perspectives on sustainability as being limited to greening and environmentalism. The alternative perspective proposed by systemics is based on taking stock of the knowledge pertaining to the complex interdependencies between nature, society (including the economy), technology and the built environment. In short, systemics offers a background that is both pertinent and pragmatic and which enables the understanding of complex problems and the design of their solutions. One peculiarity of this approach resides in its capacity to foster the coining of new, meaning-rich concepts, usable in further theoretical and practical undertakings. Examples of such concepts include systemography, complexification, syntegrity, and co-opetition. This paper proposes a new such concept, that is sitesynthesis, rooted in the spirit of a given place and time.