Campus spreads south across the Saclay plateau, between the École polytechnique and the CEA (Atomic and Alternative Energy Commission) designed by Auguste Perret in 1958. The challenge was to create an authentic neighborhood containing residents, shared facilities, and businesses. By 2025, this emblematic complex will welcome 20,000 teacher-researchers, 30,000 students, 20,000 in staff, and around 15,000 residents, across seven kilometers and over six hundred hectares. Only the organization of the landscape in an archipelago allowing for the proper composition of such a vast space, nine compact neighborhoods are thus gathered together in the interior of a “park-campus”. The expansion of the wooded valleys and hillside landscape, along with the setting up of an extensive system of parks and public spaces, provides the physical setting necessary for the smooth functioning of the archipelago. With each neighborhood being itself of significant dimension, they are further divided into inhabited areas determined within the radius of a public transport stop, each of a scale traversable by foot or bicycle. The planning and development of the city-campus will not put into direct contact the new neighborhoods with the large agricultural expanses. A vast intermediary space, the edge, is planned for with a number of different functions. It will welcome shared ecological services (humid areas, management of biodiversity), technical and sporting facilities, recreational spaces … “The chain of major places,” as defined by the urbanists Xaveer de Geyter and Floris Alkemade, is an ensemble of public spaces is in some way the main support for the campus, around which different forms of urbanization can develop. The major places determine the centers of activity, being coupled with transport infrastructure. These public spaces are surrounded by a considerable plant presence that places them in a significant manner within their landscape and built context.