“The house is a Machine that is meant to be inhabited” Le Corbusier. Tackling the construction of cluster and serial housing in a linear building suggests, to our way of thinking, the possibility of seeking parallels between the realm of group housing and trains. The train is a simple, functional object (it rolls) with a complex purpose (comfort, resilience, airtightness, speed), that has forced industry to accept the imperious need for standardisation. With experience, we have sought perfection, harmony, precision and spatial economy. All of this is not only perfection and harmony, but also beauty. In the architecture we propose, the image of the building is one of powerful volumes sliding between each other. They define a horizontal movement of one over another, both perforated by lines of windows, with various enclosure systems. If kitchens and bathrooms are regarded as fixed cores due to their fittings, the remaining space can be split up using mobile walls. The space in the house can vary, be transformed, from day to night. During the period of maximum activity by day, the walls are folded back and the beds recessed in niches under the wardrobes and passageways that line the central backbone. At night, the space is compartmented again, with bedrooms and beds appearing for the rest period. We believe our, more ambitious design proposal of raised corridors and mobile walls is not at all outrageous, and even perhaps excessively possibilistic: for practically the same cost, the dwelling gains a greater range of potential uses by being able to use the majority of the house area as a single space for multiple activities (work, leisure, games, gymnastics, parties, etc.). With this degree of continuity between rooms, we can justify the fact that the dwelling is not set on a cross plan and only opens onto one façade with a sliding window system along its full length. With this we achieve the maximum degree of profitability, given that there are four apartment entrances per landing, thus reducing the ratio between areas of common elements and dwelling space. The external construction system for the proposed volume consists of prefab concrete panels. We believe it is possible to use them in the construction of this type pf housing because they are financially competitive with conventional construction systems. The only variable that has a dramatic effect on construction is the time factor, due to constantly increasing labour costs. We can make considerable savings in the final cost simply by reducing this factor.