Since 2008, the Institute for Urban Strategies at the Mori Memorial Foundation has surveyed the “comprehensive power” of the world’s major cities and released their findings in the form of the “Global Power City Index (GPCI).” The GPCI looks at 35 global cities of varying scales and assesses them based on 69 indicators. The resulting scores, however, do not always reflect the magnitude of city scale. A striking example of this is Paris, which has a population of around two million but is third in comprehensive ranking. Furthermore, examining various indicators in details reveals the fact that an extremely high percentage of cities concentrate their primary urban functions into a centrally located area: an “inner-city.” In the case of Paris, it is safe to say that the “inner-city” is the entire city.

The Global Power Inner-City Index (GPICI) defines an “inner-city” as an area with a 5km radius from the city center, which is equivalent to the size of Paris. Of the 35 world major cities surveyed by the GPCI, seven cities, in addition to Paris, are selected for the GPICI and their inner-cities are surveyed and compared in order to identify each inner-city’s strengths. Furthermore, the GPICI seeks to examine the phenomenon of urban “polycentrism,” whereby different urban functions are not centered in the same geographical location but are spread across multiple “centers.” This phenomenon has become prevalent in many major cities since the 20th century, and areas of 10km radius are also examined in the same way as 5km radius area, and compared with the assumption that an area of this size will encompass the elements of polycentrism. This is done with the aim of ascertaining what sort of urban power weight distribution exists in inner-cities and inner-city-equivalent zones.

In recent years there has been a growing movement worldwide to tightly consolidate urban functions into inner-cities and to promote sustainable urban planning, inspired by “New Urbanism,” the “Compact City” concept and other new ways of thinking. The GPICI compares the eight target cities’ “inner-cities” using a common scale and indicators, and the results then visually reveal the characteristics and challenges of each inner-city.