This research explores the legitimation processes underpinning the implementation of specific urban policies in cities grappling with socio-economic challenges, such as in a post-industrial context. Focusing on Europe, where public authorities are seeking to enhance the socio-economic dynamics of post-industrial cities through cultural initiatives like branch museums, our research is based on a historical study of media relating to the establishment in 2012 of the Louvre-Lens museum in northern France. Within this framework, we reveal how institutional actors have performed strategies of legitimation to develop the Louvre-Lens. Our findings underscore the confluence of two primary strategies – economic and cultural –in an effort to navigate the complexities and tensions inherent in establishing a cultural offer in a disadvantaged post-industrial region. We conclude with a discussion about the broader implications of these strategies within the realm of macromarketing. We provide practical recommendations for practitioners and policy makers involved in the development of branch museums.