The extension of the head office, west wing is the last stage of the competition which Herzog & de Meuron won in 1989 and consists of four structures docked onto the ends of each wing of the existing cruciform complex erected in the 1970s. Three of these extensions were completed between 2000 and 2004. Plans for the extension to the west were taken up again in 2013.
A full set of pictures by Damian Poffet can be found here: https://damianpoffet.com/erweiterungsbau-west/
The new buildings, their height following the incline of the slope, are laid out to form distinctly different courtyards: the court to the north with the front building closes off the cross facing the mountain and is oriented toward the park; the east court with two elongated parallel buildings faces the city; the west court with the existing building and the south court at the main entrance with adjoining restaurant and cafeteria are oriented toward the entrance side of the premises.
The new building to the west forms the main entrance to the Helvetia Insurance building complex. Its significance is underscored by the structural design: the four-story office building, resting on two mighty cones, creates a spacious covered forecourt in front of the entrance. The two cones blend into the sloping topography, establishing a link between the street-level entrance and the restaurant facilities with a garden on the floor below.
The small cone to the north accommodates a conference room on the lower level. The large cone with offices rising above is truncated. The two-story space accommodates the new cafeteria, providing a unique location within the head office of Helvetia, which is open to staff all day long.
Herzog & de Meuron, 2015