Information systems are the foundation of Building Information Modelling (BIM). Connected information and consistently linked model data form the basis for collaborative construction. They enable transparent controlling and reliable risk management. Multimodels are interconnected information. The fundamentals and methods of BIM and multimodels are explained, demonstrating how process-oriented management with multimodels brings new quality to the planning and control of construction processes. The continuous BIM workflow with connected information allows for construction process simulations to be conducted in the shortest possible time. In addition to the virtual building, a virtual construction site is also created in virtual reality, providing important new insights for construction management. Construction management information becomes transparent, tangible, and comprehensible all at once. Volume 1 focuses on.