Even now, the great cathedrals of the Middle Ages overwhelm us by their imagination, technical daring and sheer scale. How could such structures be built when cities had only a few thousand inhabitants and only the most primitive machinery was available? Who initiated them? Who designed them? Who paid for them?

Through the documentary records that remain (many of which are quoted at length), and drawings and details from contemporary art, we are led into the extraordinary world of the medieval master mason.