Slates from quarries in Wales once went to roof the world. By the late nineteenth century as many as a third of all the roofing slates produced worldwide came from Wales, competing with quarries in France and the United States. This book traces the industry from its origins in the Roman period, its slow medieval development, to its massive expansion in the nineteenth century, as well as through its long drawn-out decline in the twentieth. Fifteen informative chapters cover the quarrying techniques, transport infrastructure, the lives of the quarrymen and the lasting impact of the industry on the landscape of Wales. This book is superbly illustrated with full- colour images, aerial photographs and drawings from the National Monuments Record of Wales, along with historic images and maps.