The “Diamond” is one of the icons of modern Milan. With its 30 floors, totalling 140 meters height, it is the fifth tallest building in Italy, and the tallest among those built in steel.The design choices of the functional requalification, that allowed the LEED Commercial Interior Gold certification to be obtained, were aimed at maximizing the working comfort of the BNL offices, creating healthy, pleasant and low impact environments both from an ecological and a maintenance point of view.A masterpiece of energy efficiency, the result of a multidisciplinary approach that allowed the choice of sustainable architectural and construction solutions, in perfect synergy and integration with the plants.