Allianz Tower

Arata Isozaki and Andrea Maffei devise a brilliantly straightforward structural solution for the ultrathin profile of the Allianz Tower at CityLife in Milan.

Text by Clay Risen

Milan has long been the financial capital of Italy, but until recently, it has lacked the dense verticality that marks other European economic powerhouses like Frankfurt in Germany and Paris’s La Défense. In the last few years, though, skyscrapers have started springing up around the city center, mostly to provide office space for companies like Google and LinkedIn.

One of the most watched of this new crop of tower developments has been CityLife. Located a few miles northwest of central Milan on the site of the old city fairgrounds, the complex is anchored by three towers, including one by Zaha Hadid and one by Daniel Libeskind, AIA. The third is the 50-floor Allianz Tower, which, at 793.3 feet tall at the tip of its broadcast antenna, is now the tallest building in Italy.

Designed by Tokyo’s Arata Isozaki, Hon. FAIA, and Milan’s Andrea Maffei and nicknamed “Il Dritto,” or “The Straight One,” the Allianz Tower strikes a stunning profile: An impossibly thin 79 feet deep by 202 feet long, it is composed of eight six-floor sections, with the glass in each seeming to billow out like a pillow. The curtainwall’s cold-bended, triple-glass-unit panels are affixed to a steel frame that is curved to the outside, but straight against the interior façade.

From the side, the tower intentionally resembles Constantin Brancusi’s Endless Column, Maffei says. “Our projects always start with a concept that we want to tell with architecture. In this case the concept was the idea of infinity.” Isozaki and Maffei placed the elevators and core functions at either end of the building, so “the skyscraper becomes a thin transparent sheet that light passes through,” Maffei says.

To keep the building rigid, construction crews sank 62 concrete columns 101 feet into the ground below the reinforced-concrete foundation. At the 24th floor, the two cores, also made of reinforced concrete, are connected by a steel belt truss. According to Maffei, the building is strong enough to withstand a seismic event, with some movement on the upper floors. Rather than sacrifice office space at the top for a damper, the team opted for four external, and gold-painted, steel buttresses, which anchor into the structure at the 11th floor. The two on the building’s northwest side are 196 feet long and connect to a brace in the basement; the two to the southeast are 131 feet long and anchor into a pair of support structures that house meeting rooms and cooling towers.

The Allianz Tower’s thinness is not just to show off the team’s engineering prowess. Relegating core functions to the ends allows for versatile interiors. “Our idea was to create a very flexible office space,” Maffei says. “The way of working is changing quickly and office space needs to follow this transformation.”

Project Credits
Project: Allianz Tower, Milan
Client: CityLife
Design Architect: Arata Isozaki & Associates, Tokyo, and Andrea Maffei Architects, Milan . Arata Isozaki, Hon. FAIA, Andrea Maffei (principals); Pietro Bertozzi, Takeshi Miura, Alessandra De Stefani, Chiara Zandri, Davide Cazzaniga, Vincenzo Carapellese, Roberto Balduzzi, Francesca Chezzi, Takatoshi Oki, Stefano Bergagna, Paolo Evolvi, Elisabetta Borgiotti, Giuliano Godoli, Giorgio Ramponi, Adolfo Berardozzi, Hidenari Arai, Higaki Seisuke, Takuichiro Yamamoto, Carlotta Maranesi, Atsuko Suzuki, Sofia Bedynski, Antonietta Bavaro, Mauro Mazzali, Sofia Cattinari, Taro Hayashi, Haruna Watanabe, Madoka Tomita, Ayako Fujisawa (project team)
Structural Engineer: Sasaki Associates (competition); Arup (project); Holzner & Bertagnolli Engineering, Cap Engineering (basement structures)
Façade Consultant: Arup
Fire Safety: Studio Mistretta & Co.
Vertical Transport: Jappsen Ingenieure
Lighting Design: LPA
Project Management: J&A; Ramboll
General Contractors: Colombo Costruzioni; Focchi
Construction Manager: In.Pro
Size: 81,615 square meters (878,497 square feet) above grade; 44,485 square meters (478,832 square feet) below grade
Cost: Withheld