This book assembles for the first time in a single text the full range of astronomical and engineering principles used in the design and construction of large telescopes. It aims to cover all aspects of the field, from the fundamentals of astronomical observation, to optics, control systems, and structural, mechanical, and thermal engineering, as well as such specialized topics as site selection and program management. The book is the result of the collaboration of many leading astronomers, engineers, and project managers. Their contributions have been edited to provide a consistent approach and treatment: for example, ground- and space-based telescopes are treated from a common perspective. Topics covered include: - Design Methods and Project Management - Telescope Optics - Stray Light Control - Structure and Mechanisms - Pointing and Control - Active and Adaptive Optics - Thermal Control - Integration and Verification - Observatory Enclosure and Siting