SKYDB Definitions lists a number of cities as World Cities in order to give users a clear idea of the most important building markets. This code is based on the GaWC (Globalization and World Cities) Research Network listings, but adds in the missing factor of real estate market size.

The concept behind the GaWC World Cities listing is to develop insight into the role of cities in the world order by examining the reach of transnational companies including worldwide firms and conglomerates as well as small companies which qualify as global players. The GaWC analysis examines four industries: accountancy, advertising, banking/finance, and law. Depending on the number of companies in each industry, each city earns 0, 1, 2, or 3 points on an ordinal scale. The aggregation of points in all four industries ranges from 0 to 12. Every city with sufficient business presence to merit at least 1 point is included in the categorization, and the results are divided into 4 classes of successively more elite cities: Alpha, Beta, and Gamma World Cities, and a group labeled Evidence of World City formation.

SKYDB Definitions bases its World City analysis on the GaWC concept, assigning each city its place in an extended picture of global cities. The GaWC model is expanded by the addition of a fifth industrial index, labeled real estate volume. For this, data on major buildings is gathered and fed into a similar analysis. This data includes information on major buildings (buildings with a minimum floor count or gross floor area) which are completed, approved or under construction. Using this compilation, in a manner similar to the GaWC analysis, each city is assigned between 0 and 3 points:

>1500 buildings: 3 points
500 to 1500 buildings: 2 points
200 to 500 buildings: 1 point