Military enclave, the Brest arsenal contains the economic and spatial strength of metropolitan France. This independent, secret and protected territory is commonly referred to as ‘a city in the city’ and is now at the centre of political decisions, which are well determined to change the image of the 20th century ‘mocky city’ and military by reappropriating this historic urban heart. Looking at the Brest arsenal, these parts of the city, which call into question the essence of the Brest arsenal, can be questioned: the urban area. Would they be ideal “anti-cities”? There is also a broader question of the processes that make cities today. As a prohibited pen, he highlighted the impact of a physical barrier on the city’s development. As a space dedicated only to work, he asked about the possibility of bursting and urban sprawl. As a direct branch of state power, it calls into question the concepts of national balance and metropolitan radiation.