Data centers, the material backbone of smart cities, power the digital economy and advanced digital services. Metaphors of ‘the cloud’ and ‘cloud computing’ obscure the massive computing and storage infrastructures, the resource flows and the land uses they mediate. To date, smart city research and policies have been concerned less with the materiality of enabling data infrastructures than with the material effects of increased datafication and digitalization of urban services. Only recently has urban data infrastructures’ rapidly expanding spatial and environmental footprint pushed their materialities to the forefront of public and academic controversies. Building on recent research on cloud geographies and ecologies, this article traces the politicization and emerging regulation around data centers in the Amsterdam Metropolitan Area, the self-proclaimed ‘digital gateway to Europe’. Here, after years of unconditional political support and regulatory passivity, a cascade of policy reforms has been introduced to confine data center growth. Nevertheless, severe urban governance challenges remain in mitigating data centers’ massive electricity, resource and land demands, and in exploiting their residual heat. We thus advocate broader dialogue across the affected policy fields and broader publics about which political objectives merit prioritizing given the constraints of available electricity and land.