Photos: Thies Wachter

Situated close to Hardbrücke railway station in Zürich, Gigon & Guyer Architekten’s Prime Tower and its three annexes, the Platform, Cubus and refurbished Diagonal, are part of a former industrial site that is being developed as a business and residential district, masterplanned by Diener & Diener. Currently the tallest building in Switzerland, the 126-metre structure has an irregular octagonal plan with retail spaces at ground level, offices on the upper floors, and a restaurant, lounge and bar on the top floor.

The cores and emergency stairs are positioned to allow up to four tenants to occupy each floor, or alternatively, for a single business to take several floors with internal atriums and staircases. Additional office space is created on the higher and therefore more sought-after floors, by the projecting floor plates. These also result in greater spatial diversity. The cantilevered projections are supported by slanting reinforced concrete columns, which run over two- or three-storeys. Green-coloured, triple-glazed, frameless window units give the polygonal structure a multifaceted appearance. To enhance working conditions, and meet the requirements for smoke ventilation, alternating windows can be opened parallel to the building.

Ground floor and typical floor plan

Project team
Architect: Gigon/Guyer Architekten; structure: Walt & Galmarini, Dr Schwartz Consulting, Dr Lüchinger & Meyer Bauingenieure, Bänzinger Partner, Richterswil and Freihofer & Partner, services: Hefti Hess Martingnoni, PB P Berchtold, Hans Abicht; landscape: Schweingruber Zulauf; main contractor: Losinger Construction, Karl Steiner; photos: Thies Wachter.

First published in AT228, May 2012