The town hall of Villejuif wants to offer a new cultural center for its citizens by constructing two movable and local libraries who can take place in different city neighborhoods. Each unit, of 230 m² (2475 sqft), aims to be a social condenser using culture and media as interface. They are local services made to promote cultural diversity and generations crossovers. We work on an architectural strategy of differences in unity. We aim to conceive a building which can adapt itself to any kind of site or orientation, offering different properties (light, opening, volume) and that can be welcoming even if it is meant to be removed. The project is based on a rectangular unit which repeat itself to create a sequence with variation in two axes (plan and section). The “cascade” effect gives to the libraries a multiplicity of readings. We conceive the two buildings with a mirror effect: they are the same but different. Both buildings share a similar organization. The lower volume is dedicated to the fixed services (storage, toilets and office) and the main volume is free for the library space itself. This main volume can adapt to different activities. A movable partition wall allows to divide the main space into a smaller unit for lectures, video projections, workshop, etc. The movable furniture, which can be stored, allows to free the space for gathering and other events. The structure of the whole buildings is made in wood (main structure, walls, slabs, wall finishing). It was built off site and assemble on site within five months included the interior finishing. This choice of structure allowed us to minimize the impact on the site thinking about the removal later on.