The more you observe the sequence of works of Lacaton & Vassal architects, the more there is a belief that this sequence has some similarities with a musical form that was particularly appreciated by composers of the music of Classicism and Romanticism: a theme with variations. Its principle is familiar: starting from an often simple musical cell, a series of movements develops that have their own character, yet all of them keep coming back to the starting theme. A consistent art, it uses all the means provided by composing, the rhythm, the tonality, the counterpoint, in order that the original musical cell can undergo multiple transformations, but nevertheless still remain recognizable. This is exactly the impression that we have with every new achievement by the architects Lacaton & Vassal. This is also the case with 59 social housing apartments completed last year in Mulhouse, a new and original variation of the same spatial concept conceived more than 20 years ago. It is significant that this concept was already implemented in their first built project, the House Latapie (1993). A modest building, but it would serve as a matrix of their entire subsequent work. In even more modest form, it contains two elements that make, one might say, its dna that we can find in all their later achievements.