Digital twins have received increased popularity in the last decade thanks to the numerous advancements in various scientific fields of software and hardware. The latest achievements in sensors, actuators, internet of things, machine learning, artificial intelligence, data storage and management have improved significantly the efficiency of their application in several sectors (including manufacturing, aerospace, healthcare, infrastructures, vehicles, supply chain and logistics etc.) with partially different characteristics. One of these fields that receives a lot of interest from various research groups is smart cities. Smart cities are urban areas that make use of the latest technologies and of available data sources (in most cases in real time) to improve the living conditions of the citizens and manage efficiently and safely the available public resources, data and infrastructures. The main goal of this chapter is to make an introductory presentation of the most important features related to the two main terms according to the literature, to describe the statuses of them and to present certain goals for the upcoming years. Finally, an attempt to evaluate how realistic and prompt 107 Third International Scientific Conference such an implementation can be in city of Trikala Greece will be attempted with respect to the maturity levels of specific digital twins’ applications.