La Defense presents an iron grey curtain to the city, but its inner courtyards are a profusion of ever-changing, euphoric, brilliant colours: the colours of the rainbow. This chromatic virtuosity, the key concept in the project, is made possible by a dichroic film capable of changing colour depending on the source of light with the aid of special crystals, designed by 3M to coat perfume bottles. Applied to glass cladding in architecture, it transfigures the material.
Thus architecture sheds its static character, its definite moment or inertia and acquires the poetics of becoming, of variability, and with it the richness of change. The buildings vary not only in colour, but in height as well: from 5-6 to 3-4 floors, the top one of which is often twice as high as the others, to meet the different requirements of the companies which have their offices in the complex.