The ITU-T Focus Group on Smart Sustainable Cities (FG-SSC) concluded its two-year study in May 2015 with the delivery of 21 Technical Reports and Specifications to provide the foundations of subsequent ITU-T standardization work. This compendium of the reports and specifications released by the Focus Group will assist the studies of all decision-makers with smart-city ambitions. Smart Sustainable Cities will contribute to the achievement of the Sustainable Development Goals by leveraging information and communication technologies (ICTs) to set cities on a development course characterized by environmental sustainability, resilience, and equitable social and economic growth. The ITU-T Focus Group on Smart Sustainable Cities encouraged collaboration among the many stakeholders expected to contribute to the development of Smart Sustainable Cities. The diverse group analyzed research on the topic of smart cities, addressing gaps in research and establishing a basis for the development of relevant international standards.