Some countries have a single large urban agglomeration (e.g. Argentina, Philippines, France or South Korea). Others have three or more major agglomerations (e.g. India, China, Italy or the Netherlands). Countries like Russia and Bangladesh have two big agglomerations. This page is my initial attempt to visualise all this.
For a given country, the y-axis shows the ratio of the population of the largest to second largest agglomeration. The x-axis shows the ratio of the second largest to third largest. The size of the circle reflects the size of the largest agglomeration in that country.
The red lines show a 1:1 ratio.
Mouse over country name to highlight circle.
Data from Thomas Brinkhoff: The Principal Agglomerations of the World