Megaprojects and their public spaces have often been criticized as sites of commodification and privatization. Without questioning these trends, a growing body of research affirms the contingent nature of projects, requiring in-depth empirical studies. This paper focuses on the implementation of Grand Paris Express, a transport mega-project, from a public-space perspective. We draw on the case of La Courneuve Six-Routes station to analyze the growing complexity of public space governance in Greater Paris. In so doing, we offer an additional contribution to the literature. The main driver of change in public space policies is interterritorial governance between local, metropolitan and national levels, not private actors. Moreover, the design principles and implementation processes do not provide for iconic, commodified and sanitized public spaces. However, in their current configuration, the politics of these public spaces remains ambivalent, because of the importance of real estate development in the network's future implementation.