Today the question of how to work in the continuous contemporary urban landscape, is a big concern for urban development professionals. Still marked by the modern obsession to define the building forms, a vision influenced by the functionalist movement of the Thirties, these same professionals have lost their means of working sustainably in a contemporary city which is both continuous and fragmented, like an individualised collection of various materials and shapes without urban links, spreading out without limits in the overall landscape. In this chaos, an urban approach has appeared, changing the interest from the building to its landscape, from the built to the non-built, and above all from the filled to the void, and offers a new approach more adapted to the context of today's urban environment, capable of creating links with the non built, of offering new urban materials through the 'non urban', and generating public spaces in the presence of 'non-form' buildings. This approach, which here is called The void. New urban strategies, works with the 'non-materials' such as the landscape, the infrastructure or the programmes, and tries to meet the challenge of a new urbanism in the contemporary city. To understand this, the thesis will strive to explore the chronology of this idea through its different chapters. A 'prehistory' will provide an understanding of the origins of this, via its discoverers, pioneers and precursors and will present an astonishing picture of first attempts to define the urban environment via the void. The case of Melun-Senart, the urban strategy developed in 1987 by Rem Koolhaas and his Office for Metropolitan Architecture (OMA), considered as the starting point for this search and as the masterpiece of the Void approach, will demonstrate the extremely innovative phenomena which resulted from what it called by its author as the "Strategy of the void". Putting this into perspective in the work of Rem Koolhaas will reveal a dense web of projects and writings on, or with the void, which again reinforces the idea of its pertinence. The exploration of the artistic fields and parallel philosophies, will demonstrate the pre-existence of the 'void' concepts amongst the protagonists and will prove the huge influence that they had in the construction of this new urban idea for the architects and the urban planners, and in particular Koolhaas. Finally, other contemporary urban protagonists will illustrate through their projects and their writings, a variety of approaches for the void up to the present day. And right at the end, an experiment through the void projects of the author, will offer an introspective vision of the process. More than two decades after the 'Strategy of the void' this approach goes beyond the diagrammatic stage of a competition, confirming not only its pertinence, but also its ability to provide answers that are both varied and renewed to the extremely complex and confused situations that are to be found in today's urban environment. This new way of conceptualising the urban landscape by the void, the reference for the dense area of the historical city, is replaced by the informal void of the contemporary city considered as the very identity of this new continuous urbanism and shows itself ultimately to be the void. a new urban strategy.