Completed in 1973, this Modernist monument quickly became known as the monkey mountain for its massive, shut-off volumes. It was Europe's largest office building. To make the building more responsive to its context on the Amsterdam river Amstel, we stripped it back to its structure of staggered volumes, replacing the thin bands of windows on its white tiled façade with floor-to-ceiling glass. Planted roof terraces and a sky bar on the roof further open up the building to its environment. By dematerialising the closed colossus we created a crisp, open and invitingly modern mixed-use building.