This book offers an engaging overview of the history of the telescope, which burst onto the world stage four centuries ago. It traces the development of the first device to extend one of the human senses, from its arrival in the Netherlands in 1608 to its use all over the world in modern science and everyday life. Along the way we enter the world of the innovators and adventurers who helped shape that story, discovering how Galileo used the telescope to create his reputation as one of the world's great scientists, what Isaac Newton was doing with arsenic and why the most advanced telescopes in the world owe so much to the science of spying. There are also less familiar stories, including the dangers of termites and some interesting uses of a well and a Model T Ford. As well as covering the well-known stories of scientific marvels like the Hubble telescope, the book deliberately broadens the approach taken by previous histories of this iconic device, looking in addition at the important development of the telescope as a modest hand-held device, and at its wider impact on culture and society. This book is being published to coincide with the 400th anniversary of the telescope.