_Digital Twin and Blockchain for Sensor Networks in Smart Cities _explores how digital twins and blockchain can be used in the functioning of the smart city. The book is divided into five sections. Section 1 focuses on the fundamental concepts of blockchain and digital twin for sensor networks in the smart cities, while section 2 describes their promising applications for managing the regular operations and services. Sections 3 and 4 deal with their applications for safe and healthy cities, respectively. The last section covers other promising applications and future perspectives of blockchain and digital twin in the urban environment. Big data from wireless sensor networks in the smart city can be integrated to accommodate the exchanging of real-time data between citizens, governments, and organizations. Blockchain technology can provide high security for large communications and transactions between many stakeholders in smart cities. Digital twins provide the use of physical models/wireless sensor networks/historical data of city operation to integrate big information under multi-discipline, multi-physical quantities, multi-scale, and multi-probability conditions. * Describes the fundamentals of blockchain and digital twin * Explains how intelligent sensor networks can be used in the smart city * Explores how blockchain and digital twin work with smart sensor networks * Discusses how future technologies can benefit the healthcare of everyday lives