Marije ten Kate is Head Urban Planner at the municipality of Rotterdam. She has extensive experience in spatial development and infrastructure planning. Marije is fascinated by how technical and environmental transitions are changing cities fundamentally (e.g. adaptation to climate change, renewable energy, circularity, new mobility, digitalisation and COVID). Since 2017 she’s leading the Rotterdam innovation program #NextCity. In this program the municipality explores alternative ways of thinking and acting to deal with the new and often unexpected spatial impact of transitions on the city. Our current planning system can’t cope effectively with the fundamental uncertainties that are caused by these transitions. How to deal with these unknowns? #NextCity Rotterdam is learning how by joining forces with several research institutes and doing experiments in real life. Surprisingly, it turns out there are many parallels between, at first glance, very different transitions.