By 2050 over 70% of population will live in urban areas, and will produce huge amounts of trash at an increasingly fasting pace. Complex questions about energy, food, refugees, money and environment affect everyone because we live in an interim period between two paradigms: the linear and the circular one. Circular thinking, collaborating and organizing with each other are the big challenges and great challenges and opportunities of the coming years. But how do we start changing the system? We need to give the system a new purpose and new possibilities with minor modifications. We need to hack our cities and re-purpose what is already there. And the only way to do that is with businesses and governments support, but most important citizens belief Sladjana Mijatovic graduated as Urban Designer at the Technical University in Delft and is Master of Science in new large-scale urban planning as in urban regeneration and transformation. From 2014 she has been working as the Circular Economy & Urban Innovation expert at the Chief Technology Office, at the City of Amsterdam. She is also the Circular Innovation Officer for Amsterdam Smart City and works with market parties and knowledge institutes to accelerate the transition to a circular model through innovations and new developments in the city.