Located in a building that dates from the early 20^th century, in the centre of Brussels, the head office of the Brussels Intercommunal Transport Company has been entirely renovated in order to meet the client’s requirement for a more dynamic and efficient image for its departments. This has been done through a functional enhancement of the premises. In substantive terms, the crux of the project lays in the complete restructuring of circulation flows within the building. Two large pre-existing, but under-utilised atria, have now been improved, having been given a new importance as places for circulation and meeting for the different activities of the company, thus becoming the new heart of the building. The reorganisation of the work spaces aims for modularity, and facility of movement and exchange. The materials used accompany the intentions of dynamism and conviviality: the white and yellow walls contribute to the ambient luminosity, while the use of wood brings a warm atmosphere. Finally, this renovation has also enabled an enhancement of energy performances and additional natural light.