A distinctive feature of the entire complex, it is the only element visible from above, looking at Milan on foggy days. Spiraling upward from the south face of Tower A is a 70 m (230 ft) cone-shaped spire. They are placed at the intermediate crosspiece of each floor and extend for an overall length of 6 km (3.7 mi). The horizontal fins consist of modular elements protruding from the outer edge of the glass. Moreover, the presence of the protruding sunshading fins marks the succession of the floors, which vary in depth depending on the building and create games of light and shadow on the glass surface. The façades of the internal concave areas are distinguished from the external convex areas due to the type of glass, which is more reflective on the outside to enhance the shape of the buildings and less reflective on the inside to allow a better interaction between the offices and their occupants and the piazza. The design and customization of the components allowed the façade solution to deliver excellent thermal, light and acoustic performances. Each unit was conceived as an independent module, including the frame, glass and accessories. It comprises four glass elements, three of which are visual and one spandrel in correspondence with the floors, and aluminum profiles.
The main cladding that distinctly characterizes the appearance of the sinuous and enveloping volumes develops above the public strip, and consists of a system of prefabricated units with a packaging thickness of only 18 cm (7 1/8”). The unit type has dimensions equal to 1.5 x 4.075 m (5 x 13.4 ft), the size of the inter-floor axis. The buildings are clad in reflective glass and have narrow, curved forms.
The envelope of the three towers includes different types of curtain walls and complementary elements that together cover a total surface area of more than 70,000 sqm (753,500 sq ft) with glass façades, ventilated stone façades, sunshades and a series of complementary elements. The design and construction of the architectural envelope of the towers and the special elements that distinguish it necessitated the creation of specific innovative solutions that were able to transform the architectural vision into reality, and to combine it with the high performances expected. The entire perimeter follows the circular layout of the lot, with openings at several points. To this end, Tower C, the lowest, was placed on the side with the smaller buildings, Tower B in front of the station and Tower A, the tallest, at 217.7 m (714 ft), towards the park. The three buildings face the piazza, Towers A (UniCredit Tower), B and C were designed to integrate with the surrounding area, characterized by pre-existing buildings and various other structures. The unity of the complex is emphasized by a single ring-shaped canopy that runs around the circumference of the piazza, connecting the podiums of the three towers and bringing the public spaces of the piazza inside the office buildings. This delicate task is accomplished by the building envelope, consisting of a cladding that unifies the towers through moldings and stringcourses that wrap around the sinuous forms and curves of the volumes.