Juan Navarro Baldeweg´s installation Interior III (1975) was exhib ited at the Center for Advanced Visual Studies (CAVS) of the Massachusetts Institute of Technology (MIT) in 1975, as a compendium of the research that he began to develop around the exploration of optical phenomena and color, seeking to investigate those mechanisms that allow observation, apprehension, and the understanding of the environment. The installation is part of a series, in which, starting from empty rooms, Juan Navarro Baldeweg explored various concepts and ideas, which, over time, came to be what he called the essential variables that can be found in his architectural designs and works of art. The study of this instal lation and the optical pieces that he created in this context can help us understand in depth some of these variables, which ended up laying the foundations on which his unique professional career is based.