This book studies the historical development of the tunnelling industry, with emphasis on the technical innovations on which advances in that industry have depended. The main part of the book comprises a detailed examination of the major technical advances in both hard rock and soft ground tunnelling, discussing established methods such as tunnelling machines, compressed air tunnelling and prefabricated tunnel linings, as well as more recent topics such as pressurised face shields, extruded linings, hydraulic rock drills, and small-diameter tunnelling systems. In addition, the emergence of a highly innovative tunnelling industry in Japan is discussed; a parallel being drawn between this development and that in nineteenth century Britain. From these considerations, the conditions that have allowed technical innovation to flourish in the tunnelling industry are identified, leading to a more general discussion of the nature of technical innovation in this industry and beyond.