In order for the turnaround in the construction industry to succeed, material resources must be fully reused and recycled. Single-origin and low-pollutant building materials, which are used in reversible component joints and are simply joined, are the basic prerequisite for the circular design of buildings. This handbook explains how to plan and build according to the circular principle. It shows the past and present of circular architecture and analyses the fundamentals of single-origin construction in terms of methodology, material and construction. Joining and connecting techniques will be discussed, as well as the choice of materials in general and the life cycles of individual layers and their functions.