This book is the official history of the Anglo-Australian Telescope (AAT), which was built at Coonabarabran in New South Wales beginning in 1968; it came into operation in 1974. The telescope is part of the Anglo-Australian Observatory which provides facilities for research in optical astronomy for scientists from Britain and Australia. Between them, the authors of this book were all involved in different capacities throughout the development of the telescope. As such it gives a detailed and personal record of the scientific, administrative and political developments from the moment negotiations began to the present day. The AAT has been and continues to be an outstanding success and can lay claim to being the best instrumented telescope in the world with a very wide capability and high sensitivity.