This project, won in an international architectural competition, involves a re-massing and full refurbishment of the tower CB31 of 1974, in La Défense, The building is one of the tallest in La Defense and the new silhouette is clearly visible on the skyline. Besides its new visibility from afar, the new design carefully reconfigures the public space at the base, reinforcing the connections of the building to its surroundings.

On the interior of the building, walls were knocked down to improve lettable space, increase daylight to the offices and to enhance the sense of connection in plan and in section. The design increases the lettable area and brings core to wall dimensions up to current market standards, by extending the floor slabs. New sky gardens, linking several floors, create casual spaces for meeting and exchanging ideas.

The design overcame several challenges related to the existing concrete structure. The stability of the existing building was found to be not up to the current code requirements, leading to extensive structural modifications. Columns and shafts throughout the lower third of the building had to be encased in additional concrete in order to alter and spread the load path down through the building.