As a European city network, it is Energy Cities’ mission since 30 years to connect local and regional governments with each other. Twinning is a particularly powerful tool to make sure cities can learn from each other in a lasting and rather privileged partnership. Even though it may require time and resources, we have always seen that the final outcomes were very positive on both sides. By working on a same climate and energy challenge, cities get mutually stimulated, especially when they can collaborate with peers in other countries. In times of COVID and climate urgency, cooperation and solidarity across borders is needed more than ever – on both sides of the Mediterranean.