In the course of the project it was decided to look at two data areas more specifically. Firstly, the ancient world, the point in time when the first urbanisation began and the way to the first million. On the other hand, from 1900 to the present day, the period in which large cities grew into mega-cities.

In the first period, a consideration every 500 years was chosen. For the second period, growth is considered every 10 years.

We had three data sets at our disposal, each containing data at different points in time. These three data sets were combined to obtain a comprehensive basis.

Further parameters were obtained by simple research.

The data have been rounded for practical reasons.