The project roots can be found in two architectural streams. The first is the age-old history of imaginary and/or impossible architectures. From all times, architects have been trying to imagine architectures freed from the laws of nature : castles hovering in the air, cities floating on water, buildings reaching the sky, buildings like mountains, monuments defying the law of gravity, palaces built for eternity, animated houses responding to the owner’s desires... Many paintings and engravings along architectural history show these dreamy constructions of mind, which at times are approximately transposed to real structures after some technological breakthrough suddenly brings them closer to the realm of possible buildings. Among them, the most fantastic is certainly the idea of a hovering architecture, maybe because there is no possible approximation to it. A skyscraper gives a good idea of a “building that reaches the sky”; the lifespan of a pyramid is long enough to infuse the passerbys with a feeling of eternity; some large buildings covered with gardens are rather precise representations of small mountains ; Venice, though builds on thousands of wooden posts, materializes pretty well the dream of a built mirage, a city floating over its own reflections. But representations of hovering or flying architectures are seldom encountered. The closest evocations are certainly the vaults or cupolas of certain religious buildings; the dome of Hagia Sofia, in Istanbul, has been described as the biblical celestial city, floating in the air; the upper part of late-gothic cathedrals is an aerial mix of stone and light whose lightness seems to defy gravity to achieve a high level of spirituality. But these impressions of flight and hovering are achieved only at certain particular places, through a tremendous expense of materials and expenses for the rest of the building : the piles that counteract the thrust from Hagia Sofia’s hovering cupola have been described as “massive heaps of stones”.