The relationships between cities and underlying groundwater are reviewed, with the aim to highlight the importance of urban groundwater resources in terms of city resilience value. Examples of more than 70 cities worldwide are cited along with details of their groundwater-related issues, specific experiences, and settings. The groundwater-related issues are summarized, and a first groundwater-city classification is proposed in order to facilitate a more effective city-to-city comparison with respect to, for example, the best practices and solutions that have been put in practice by similar cities in terms of local groundwater resources management. The interdependences between some groundwater services and the cascading effects on city life in cases of shock (e.g., drought, heavy rain, pollution, energy demand) and chronic stress (e.g., climate change) are analyzed, and the ideal groundwater-resilient-city characteristics are proposed. The paper concludes that groundwater is a crucial resource for planning sustainability in every city and for implementing city resilience strategies from the climate change perspective.