Master plan of the old Spanish walls
The Leien are a series of streets that largely follow the route of the Spanish fortification walls as it was constructed in the 16th century. In the modern days, the entire road on Leien has become a chaotic distribution line of trams, car and buses, neglecting pedestrians and cyclists. This complicated 60 meters wide traffic boulevard along the Leien has formed a huge traffic barrier and becomes one of the main contributors to the air pollution.