Bringing nature back into our cities – what are the do´s and don’t´s – and how can we put a value to blue-green infrastructure. The natural green and blue infrastructure of the cities provide to the city and its inhabitants services like storm water management, air purification, there is a growing interest in the role of functional nature in the cities and these services and functions can be enhanced with evidence based design. We present case studies where the value of green and blue infrastructure is highlighted and project examples how these functions and services have been enhanced.