This book explores the core value of Gulangyu’s historical environment, using outstanding universal value and Sino-foreign cultural exchange as the framing aspects, based on the requirements for Gulangyu being recognized as a World Heritage Site. Using the existing historical buildings and sketches as prototypes, the book provides a scholarly discussion on China’s modern urban architecture and the ways in which its historical environment has been transformed, especially the reuse of design in its modern urban architecture, explored in six case studies on Gulangyu.