Switzerland has a dense network of cities, where large, medium and small cities are complementary. The plateau is very densely populated with about 450 people per km2 and the landscape continually shows signs of human presence. The weight of the largest metropolitan areas, which are Zürich, Geneva–Lausanne, Basel and Bern tend to increase. In international comparison the importance of these urban areas is stronger than their number of inhabitants suggests. In addition the two main centers of Zürich and Geneva are recognized for their particularly great quality of life.