Three important themes come together in the project for the electric power station on the Appia: an industrial complex that had to be inserted into the natural landscape; a large-scale building type that had to be given architectural quality; and the philosophy and image of the client. We decided to express in architecturally equivalent terms the anima of the plant itself, namely the principle of frequency. Just as the physical law of frequency governs the universe of electricity, so too the architectural profile of the entire structure consists of a chromatic frequency. Using three shades of blue, the darkest at the bottom and the lightest at the top, we fragmented the surfaces with horizontal geometric patterns and dematerialized the volumes which, due to rigorous technical requirements, were necessarily large.Like the choice of materials, the palette of colours arranged in a frequency merely declares itself: a presence that is as pleasing as it is better by definition.