This book is not about construction, although you will learn about building codes and practices. It is not about tactics, although the information gained by knowing a floor plan will undoubtedly affect them. Instead, this book is designed to provide a quick and simple method of confidently determining floor plans by using outside architectural features. It assumes no knowledge of construction or tactics and is designed to be useful whether it is read cover to cover or occasionally referred to as a reference. It provides time-tested, tried and true principles that any tactician can use to determine avenues of approach, observation and fields of fire, obstacles, and cover or concealment, not to mention where a suspect might be most vulnerable. Using this essential tool for quick and clear comprehension of tactical diagramming, even a novice tactical planner will learn to use windows, doors, vents and other clues to confidently determine interior features. After reading this book, it will be clear that the proverbial "glass house" is in the mind's eye!