Architects Kees Dam, Wilhelm Holzbauer and the city of Amsterdam commissioned a group of artists to make proposals for the new combination city hall. Each artist was free to pick a location in or around the buildings. Lucien den Arend chose for the entrance area in front of the main opera and music theater entrance as well as the inner court, which has a visual connection with this exterior space.
The two geometrical constructions align with the perpendicular volumes of the architecture. The tabgent diameters are in line and stress the length of the inner court. The vertical construction mirrors the glass cylindrical windows of the STOPERA. At the same time ithas its own reflecting surface. The height of the half circle projects above the walkways on the second floor. Because of its shape it reminds us of a shark's fin reminding us about what is below the surface. It also seems to act as a wheather vane pointing in the direction of the inner court's axis, thus accenting its length.