Philips Industries commissioned Le Corbusier to build their pavilion for the 1958 World's Fair to be a showcase of their technology. Iannis Xenakis was working for Le Corbusier at the time and ended up designing the building as well as writing music for some of the spaces (Concret P.H.. Le Corbusier designed the visuals for the inside and chose Edgar Varèse to create the music for the main space. It was an extremely complex installation with 350 speakers, all sorts of lights, slide and film projectors, sculpture and more. Xenakis' music and architecture was heavily based on mathematics, especially hyperbolic paraboloid shapes. Edgar Varèse worked in Philips then new sound studio in Eindhoven with two full-time technitions to create the main musical piece. Le Corbusier worked with his firm to create the visuals.
I am personally fascinated by this piece first of all because of the scale and integration of it. Everything is coordinated as one piece including the building itself. I also think it would have been an incredibly immersive and intense experience.