Stacking was one of man's primordial activities, according to Semper's classification. This project of 25 sustainable dwellings seeks to build by stacking concrete tubes of almost square section (3.65×3.20m) that, like printed circuit bases, maintain in them all the invariant elements of the house. The clarity of the compositional reading of the architectural model towards the square is resolved in five floors plus recessed attic, and determines the character of the building as well as that of its linked free space. The circulation spaces to each dwelling contribute to the intimacy unaltered by the communication that is privately established to each dwelling cell, through the vertical courtyards in the access, as well as the penetrations of light from the exterior from calle Gofiones.