The “123” diagonal is an “orientation building” which shows the entrance of a new district of Barcelona, and which indicates the way to down town. The interplay of architectural volumes creates a building in motion and produces a large terrace giving views over the sea. A dynamic building which gives energy and movement to the platform office. This sculpture made by black glass is striated by reflective and thin shiny silver lines. These parallel lines of different thickness filter natural light and provide visual and thermal comfort inside the building. Like on a music staf, offices, such as notes, are divided according to the needs and their development. At night, the black façade disappears and the inside of the building lights up and becomes transparent.