Written by two authors with extensive knowledge of slate quarries and the Blaenau Ffestiniog area, this book surveys the network of railways and tramways that were built to extract the slate and then to transport it onwards to its markets, where it 'roofed the world' Slate created Blaenau Ffestiniog, turning it into one of the most important towns in North Wales and though the industry has largely gone, its legacy lives on, not only in the slate tips that dominate the skyline but also in the surviving railways that add to the town's prosperity today.