This book discusses the architecture, design and implementation of critical components of Sustainable Smart Cities to support governance, transportation, energy, healthcare, factories, technologies, securities, agriculture and education. The authors discuss the background of sustainable smart cities architectures and technologies and describe the problems that arise in design and implementation.  In particular, this book discusses a proposed, 6G-based framework and architecture of IoT based sustainable smart cities. The authors describe the use of artificial intelligence in many zones of cities to increase the system's performance and efficiency. With the detailed discussion of energy management in smart cities, they have also presented how Internet of Vehicles (IoV) uses wireless communication and sensing technology to establish a network of information exchange between vehicles, infrastructure, and the environment. The discussion also includes Internet of Medical Things (IoMT) as well as Unmanned Aerial Vehicles (UAVs) for IoT based sustainable smart cities. This book explores societal, economic, and practical reforms that would promote smart cities, based on a variety of case studies.