Since the 19th century, these districts have grown together into a large complex with a vast industrial landscape, inhabited by some 7.3 million people, it is the fourth largest urban area in Europe after Moscow, London and Paris.
These districts have grown together into a large complex with a vast industrial landscape, it is the fourth largest urban area in Europe after Moscow, London and Paris. This is since the 19th century. A vast industrial landscape is inhabited by some 7.3 million people.