An austere building wrapped in metal consists of two blocks.  The shape respects limits resulting from the complicated operation of the lock chamber. A belt window along the whole perimeter provides views to each side. Membrane structures lining the whole parapet’s perimeter symbolize a wavy water surface and at the same time refer to sails.  They also provide necessary shading and protect the staff against sun glare. Harmonizing with the surrounding nature and the delicately installed new technical shape is the basic criterion of these control towers. These structures build on a premise that it is important to respect a landscape and not push it back; on the contrary, contextual and harmonic structures must be built in this very specific environment.