“Our work is experimental; but experiment is often more important than the safe way. We are well aware of the deficiencies in our work, and we can safely say that we have learned much from it.” Ludwig Mies van der Rohe in an address to members of the Deutscher Werkbund. Stuttgart, 20/09/1927 (Kirsch et al, 1989 p.7) At the beginning of the 20th century, architects have been operating in a shifting context regarding technical and aesthetic conventions. In 1927, a group of seventeen international architects constituted and conducted by Ludwig Mies van der Rohe realised the Weissenhofsiedlung as a life-size experiment and a demonstration of a “new art of building”. This research sheds new light on one of the first modernist urban and architectural projects and it reveals the gap between its technical and aesthetic features. While the architects call on a multiplicity of constructive and structural solutions in order to realise the twenty-one buildings, they all obeyed to a radical choice of minimalist aesthetics. In this case study, a comparative analysis of the projects was carried out. The re-drawing of all plans is the base of this research through drawing. Furthermore information from historical and contemporary sources on the projects was gathered, including their construction techniques and on the discussions among the architects. In the analysis, comparisons were made between structural and spatial layout on the one hand, and construction materials and the overall architectural image on the other hand. The buildings of Peter Behrens in masonry, of Ludwig Mies van der Rohe in steel, of Hans Poelzig in wood and of Jacobus JP Oud in not less than six different types of concrete, all of them showing only little variations of volumes in white cubes, bring to light the discrepancy between form and construction. The comparison with other projects of this period, dealing with visible materials and even pitched roofs, demonstrates that the minimalist aesthetics were a deliberate and radical choice of the modernist architects. The results of the research are twofold. First, it displays a surprising large gap between technics and aesthetics, in complete contradiction to the modernist dogma of the “constructional truth”. Second, it exposes the experimental character of the projects largely silenced by the following review which was instead focused on celebrating the birth of the International Style, identified as a minimalist aesthetic of white cubes. As such, the choice of reduction of aesthetic codes is identified as operating as a two sided medal of radicalisation in architecture: A priori, it generated a coherence among the different projects at Weissenhof. A posteriori, the same choice of reduction had been pursued to contribute to the mystery of a root- and timeless modernism. Eventually, the research allows a renewed, which means more detailed and critical, look into one of the first modernist urban and architectural projects. About 90 years after the Weissenhof exhibition, architects are again struggling with a shifting context. Various and simultaneous crises are again questioning the methods and conventions of our practice and once again, new technical and aesthetic solutions are to be tested. The study of the example of the Weissenhofsiedlung reminds us that such solutions are generated in collective processes and that an experimental approach (including sometimes doubtable choices) is able to renew of technical and aesthetic conventions.