Diamond Tower – BNL Milan

The steel and glass diamond of the Varesine Business District

Torre Diamante—known in Milan as the "Diamantone"—is one of the symbols of the transformation of the Porta Nuova area. It stands between Viale della Liberazione and Via Galilei, in the heart of the new business district, exactly where the old Porta Nuova train station once stood. Today, it houses the Italian headquarters of the BNP Paribas Group, becoming a landmark of Milan's new business district.Wikipedia)

Main data and urban insertion

The tower is approximately 140–142 m high, with 30 floors above ground and 4 underground levels, and is flanked by two lower buildings, the so-called “Diamantini”, which complete the Varesine Business District office complex.
With a base of approximately 30 x 50 m and a total surface area of over 30.000 m², the building can accommodate more than 2.000 people and is currently the tallest metal-framed skyscraper in Italy, as well as being one of the giants of the Milanese skyline. (Wikipedia)

The intervention is part of the larger Porta Nuova Project, which redesigned the entire Garibaldi–Varesine area with a sequence of public spaces, pedestrian walkways, and new plazas, all the way to the Biblioteca degli Alberi. Torre Diamante participates in this vertical landscape, interacting with the nearby Unicredit Tower and the Porta Nuova residential complexes, in a play of reflections that constantly changes throughout the day.

Architectural concept: a multifaceted volume

The masterplan of the area and the architectural project are signed by the studio Kohn Pedersen Fox (KPF), with the Italian-American architect Lee Polisano, supported by the Paolo Caputo studio and by Jacobs for the executive development.

The underlying idea is that of an irregular, faceted volume, reminiscent of the cut of a precious stone: the faces of the prism are not parallel, the edges are inclined, the glass surfaces bend, generating a sequence of planes that react differently to light. The result is a compact but dynamic mass, which changes perception depending on the point of view and the weather conditions.

The glass and aluminum curtain wall is modulated by a dense mesh of vertical mullions that emphasize the verticality of the volume, while the inclination of the columns and exterior surfaces produces iridescent reflections, veritable "glow" effects that justify the tower's name. The summit is also contoured: the tip is illuminated at night with changing colors, making the building a recognizable urban landmark on the Milan skyline.

At its base, the volume opens towards the public space with a more transparent and permeable ground connection, designed to dialogue with Piazza Lina Bo Bardi and the pedestrian system that connects the Porta Nuova area to the surrounding areas.

Structure: the tallest steel building in Italy

From a technological point of view, Torre Diamante is an interesting case because it adopts a metal load-bearing structure for the external frames, combined with a central reinforced concrete core that houses the stairwells and elevator shafts. The building was designed by the engineering firm Arup, with contributions from other specialists for steel systems and core-skeleton interaction checks.

The main elements:

Inclined perimeter columns with respect to the vertical, which follow the geometry of the elevation and represent one of the most complex aspects from a structural point of view.
Steel beams IPE/HE in class S355, collaborating with corrugated sheet metal floors and additional concrete casting (thickness 15–20 cm), to obtain rigid diaphragms that are light and quick to assemble.
Columns and external bracings in high performance steel (up to S460), with bolted end plate joints sized for very high design axial forces. (mza-structuralengineering.com)

This combination allowed for remarkable slenderness with limited weight, speeding up construction and reducing the impact on the urban context during construction. The result is a building that, while appearing monolithic, is actually a sophisticated exercise in steel engineering.

Envelope and energy performance

The casing consists of a continuous glass facade with cells, with selective laminated glass that limits direct radiation and improves interior comfort. The choice of laminated glass instead of tempered glass is interesting, ensuring greater uniformity of the façade plane and avoiding optical distortions (wavyness) typical of some heat treatments.

From an energy perspective, the tower is one of Porta Nuova's "high-performance" buildings, designed to reduce consumption and integrate renewable sources. Torre Diamante has obtained the LEED Core & Shell certification – Gold level, recognition that attests to the attention to sustainability: quality of the envelope, control of internal loads, efficient management of water and plant systems.

The interior is organised according to a typology now consolidated in contemporary executive offices: central core of services and distribution, and large, free perimeter surfaces, designed for open-plan offices or flexible layouts. This choice allows for maximum use of natural light and views of Milan, especially on the upper floors, which offer panoramic views of the city and the Alps. (Wikipedia)

Interior spaces and work models

The interiors are designed to accommodate a contemporary banking headquarters, with highly configurable floor plans and common spaces that function as meeting places. The intermediate level houses a restaurant and cafeteria for staff, located around the 15th floor: a glass-enclosed space with a 180° view of Porta Nuova and the historic center, emphasizing the relationship between new ways of working and environmental quality.Infobuildenergia)

Iconic tower of the new Milan

Completed in 2012, Torre Diamante is now one of the most recognizable landmarks of Milan's new verticality. By day, it works on the reflection of light and the dialogue with neighboring buildings; by night, its illuminated tip transforms it into a luminous sign that directs the gaze towards the Porta Nuova skyline.

Photographs taken in June 2025