By 2015, this is projected to be what demographers inelegantly but accurately call the largest "urban agglomeration" in the world, with about 28 million people.
It's all about accelerated agglomeration in the capital: the network, innovation and growth benefits that accrue from critical mass and economies of scale.
The second most populous city in the country, it is a major component of the Tokyo-Yokohama metropolitan area, the largest urban agglomeration in Japan.
It is now the third most-populous city and largest urban agglomeration in the state and is a major rail and road junction.
But the greater Paris region, known as the Île-de-France, sprawls for kilometers and is home to 12 million people, making it the largest urban agglomeration in the European Union.
At the opposite end of the scale, in terms of development and efficiency, the Tokyo metropolitan region remains the largest urban agglomeration in the world with a population of 38 million people.
With Aix-en-Provence it forms the second largest urban agglomeration in France, and in association with the outport of Fos-sur-Mer, about 23 miles (37 kilometres) to the northwest, it is the country's largest seaport.
Fig. 1 Concern-based agglomeration in the Health Watcher system.
Fig. 2 Intra-boundary agglomeration in the OODT system.
Fig. 4 Cross-boundary agglomeration in the OODT system.
Fig. 5 Hierarchical agglomeration in the OODT system.
