In September 2014, the ten largest core cities in Switzerland joined forces to form the Interest Group Large Core Cities IGGK. The IG works as an internal body of the Swiss Association of Cities to strengthen it in the enforcement of its concerns. The IG Grosse Kernstädte primarily serves the informal exchange of experience, the deepening of topics that particularly affect the large core cities, networking and the joint implementation of projects. As the largest city in Switzerland, the city of Zurich plays a core role in the IGGK.