The extension of the WHO Headquarters complements the facility from the 1950s, whereby the existing plinth building is continued and takes up all public functions. In contrast to the modernist linearly organised office complex, the new building is lower than the existing one and offers a compact, horizontally organised, and flexible office world. The new mezzanine floor acts as the backbone of the new pedestal and connects the existing complex with the new building: all public functions are accessible from this ‚Rue intérieure.‘

A seven-storey office building with 800 workstations is enthroned on the plinth. The horizontal organisation of the floors allows flexible division of the offices, half into individual offices and half into open group workstations. Double-storey loggias organise both the façade and the floor plan, bringing daylight deep into the centre. A multi-storey atrium with several spiral staircases offers visual and physical relationships between the floors.