Switzerland has a dense network of towns, where large, medium and small towns 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 three main centres of Zürich, Geneva and Basel are recognised for their particularly great quality of life.