Abstract
This chapter introduces smart cities through the lens of system-of-systems engineering (SoSE), positioning contemporary cities as complex socio-technical ecosystems composed of independent yet interdependent subsystems. As urban environments increasingly integrate digital infrastructure, data platforms, and intelligent decision-support technologies, traditional silo-based planning and optimization approaches prove insufficient for addressing systemic challenges such as sustainability, resilience, governance, and uncertainty. The chapter traces the foundations of SoSE, outlines its defining characteristics, and critically reviews its evolution from defense and aerospace applications toward urban and civic domains. It synthesizes key modeling, architectural, and analytical approaches used to represent smart cities as systems of systems (SoS), with particular attention to emergence, interoperability, adaptive capacity, and cross-sector coordination. The chapter further examines the growing role of data analytics and artificial intelligence as enabling yet complicating subsystems within urban SoS, highlighting associated governance, transparency, and accountability challenges. By identifying persistent research gaps—especially in empirical validation, dynamic evolution, and socio-technical integration—the chapter establishes a coherent conceptual foundation for the book and motivates the need for holistic, adaptive, and practice-oriented SoSE frameworks in smart city development.