This article assumes the premise that there is no alternative other than sustainable development. The necessary escalation to sustainability will force organizations and public administration to adopt an adequate stand to the sustainable development, mainly when it comes to the promotion of policies that shall guarantee the fulfillment of the triple bottom line (sustainability tripod) for the next generations, also respecting cultural and political issues. This research has collected data from four cities all around the globe using forty-six ‘ISO 37.120:2018’ core indicators. We have compared, using an adapted fuzzy logic model, the general sustainability score of cities in developing and developed countries. The event of trying to determine a methodology that can be used by any city of any country requires a considerable amount of researching, especially when it comes to choosing which better indicators are fit to the challenge - at the end of the article, we offer a schematic of a smart sustainable city, which we have called “sustainability mandala”. Using the same system (with different weighs for each variable,), those answers will help public managers to understand their indexes as a result of positive efforts over the indicators, always on the pursuit of a really sustainable society.