ICLEI – Local Governments for Sustainability is a global network of more than 1,750 local and regional governments committed to sustainable urban development. Active in 100+ countries, they aim to influence sustainability policy and drive local action for low emission, nature-based, equitable, resilient and circular development. They host a collection of resources and webinars about how to achieve sustainability in cities and urban areas.
Becoming a member requires a fee but many resources are online for free.