Dominique and John de Menil asked Renzo Piano in 1981 to make a museum in Houston to host their collection of primitive African art and modern surrealist art, one of the most important in the world. Madame de Menil's first request was that all works could be observed in natural light, and she wanted a space that would favor a direct and relaxed relationship between visitor and work of art, a non-monumental environment. The natural lighting of the exhibition environments is the solution that characterizes the building. The goal was to promote a mediated light diffusion in the showrooms, without losing the sense of mood swings. At the end of a long survey, a basic structural element was defined, the so-called "ferrous" leaf (thickness 25 mm) which, repeated 300 times, is the roofing platform designed to fulfill the dual filtration function: the light and the thermal screen.