New technologies are increasingly being integrated with various components to enhance the functionality of smart cities. These intelligent urban environments heavily rely on IoT (Internet of Things) communications to foster the concept of a "Smart City." This is achieved by leveraging advanced communication technologies to improve services for citizens and city administration. Smart cities have witnessed the installation of numerous IoT-based devices, where the Internet of Things is a modular method to integrate different sensors with all forms of ICT (Information and Communication Technology). This discussion offers an in-depth look at smart cities' concepts, features, and applications. It delves into intelligent cities' usage, challenges, and prospects, seeking insights from current technological advancements and perspectives, including blockchain and machine learning, within cloud and fog IoT ecosystems built on IoT devices, architectures, and machine learning techniques. Moreover, the text highlights the importance of privacy and security measures, such as blockchain technologies, in developing smarter, more secure, and resilient urban areas. It also presents a conceptual framework for the mega-events in intelligent cities, underscoring these urban centres' key ideas, features, and applications. Finally, it contemplates the impact, applications, and challenges of emerging technologies in the evolution of modern intelligent cities.