Seoul, the capital of South Korea, serves as a shining example of the potential and transformative impact of smart city interventions. In just two decades, Seoul has evolved from a chaotic and struggling mega-city into a global benchmark, all thanks to its innovative use of technology to enhance the quality of life. The revitalization of the Cheonggye Stream, hidden beneath a road for decades, brought nature back to the heart of the city. Alongside this transformation, an advanced smart transport system catalyzed a significant shift toward public transportation over personal vehicles. And a sequence of urban renewal and beautification initiatives contributed to reshape Seoul's urban landscape into a smarter, more sustainable city. In this book, we delve into the ingenious initiatives taken by Seoul's leadership to transform the city into a global smart city. Seoul's journey in smart city development offers a compelling narrative filled with invaluable insights, making it an essential resource for cities worldwide facing unsustainable, chaotic growth. It provides a roadmap for intelligent urban progress and enhancing the quality of life.