The Block Mills in Portsmouth Naval Base have long been known to students of naval and industrial history. Within this group of buildings a remarkable set of machine tools designed by Marc Brunel to manufacture ships' blocks laid the foundations for the subsequent world-wide development of industrial production-lines that used ever more sophisticated machinery to replace the work of individual craftsmen. In a very real sense, the modern world of factory mass-production using machine tools had its origins in this Georgian buiding overlooking the heart of the dockyard. The importance of the pioneering work in the Block Mills was recognised by discerning contemporaries and the building swiftly became an object of pilgrimage for many, its fame assured by its inclusion in a number of major 19th century encyclopaedias. Block-making ceased here in 1965, but a number of the machines still survive, in Portsmouth and in the Science Museum, while the Block Mills still remain much as completed in the first years of the 19th century, the interiors little altered. This book has been written to coincide with the bicentenary of the installation of the final set of block-making machinery in 1805. It covers the construction and use of the building and its machinery and aims to set the Block Mills in the wider context of late Georgian dockyard modernisation.